refactor(test): remove misleading t.Setenv in GitHub integration test

The test constructs github.Client directly (matching the Gitea integration test pattern), so setting VCS_TYPE does not affect the code under test. Remove the setenv call to avoid implying routing is being exercised.
nit: remove extra blank line before TestEnvOrDefault
2026-05-14 15:33:47 -07:00 · 2026-05-14 15:32:41 -07:00 · 2026-05-14 15:32:13 -07:00 · 2026-05-14 22:10:57 +00:00 · 2026-05-14 22:07:04 +00:00 · 2026-05-14 22:06:21 +00:00
22 changed files with 4229 additions and 188 deletions
@@ -1,17 +1,43 @@
-# This composite action is designed for Gitea Actions runners.
-# Gitea Actions supports GitHub Actions syntax including $GITHUB_OUTPUT,
-# actions/cache, and actions/checkout.
+# This composite action supports both Gitea Actions and GitHub Actions runners.
+# It detects the VCS host type by checking whether github.api_url is set
+# (present on GitHub.com and GHES runners, absent on Gitea runners) and uses
+# the appropriate releases API for version resolution and binary download
+# (REST API on GitHub, direct URLs on Gitea).
+#
+# Security notes:
+# - On GitHub/GHES (VCS_TYPE=github), inputs.vcs-url is IGNORED to prevent
+#   token exfiltration. API calls use github.api_url; downloads use
+#   github.server_url. Tokens are never sent to user-supplied URLs.
+# - On Gitea (VCS_TYPE=gitea), inputs.vcs-url is validated (https scheme,
+#   no whitespace/newlines, and DNS resolution to a public IP) before use.
+#   Python3 resolves the hostname and rejects RFC1918, RFC6598 (carrier-grade
+#   NAT), loopback, link-local, and other reserved addresses to prevent SSRF attacks.
+#   The installed review-bot binary additionally uses a safe HTTP transport
+#   (DialContext-level IP check) for all Gitea API calls at runtime.
+#   The binary also exposes a `validate-url` subcommand for use in any future
+#   shell steps that need to validate a URL before passing it to curl.
+# - action-repo is validated against owner/repo pattern.
+# - Tokens are passed via masked environment variables, not step outputs.
+#
 # Requirements: python3, sha256sum, curl (all present on ubuntu-* runners).
 name: 'AI Code Review'
 description: 'Run AI-powered code review on a pull request using review-bot'

 inputs:
-  gitea-url:
-    description: 'Gitea instance URL (defaults to server_url)'
+  vcs-url:
+    description: 'VCS server URL (only used on Gitea runners; ignored on GitHub/GHES). Defaults to server_url.'
    required: false
    default: ''
  repo:
-    description: 'Repository (owner/name, defaults to current)'
+    description: 'Repository to review (owner/name, defaults to current)'
+    required: false
+    default: ''
+  action-repo:
+    description: 'Repository hosting review-bot releases (owner/name). Defaults to github.action_repository or rodin/review-bot.'
+    required: false
+    default: ''
+  action-repo-token:
+    description: 'Token for downloading release assets from action-repo (defaults to github.token on GitHub, reviewer-token on Gitea). Required for private repos.'
    required: false
    default: ''
  pr-number:
@@ -19,7 +45,7 @@ inputs:
    required: false
    default: ''
  reviewer-token:
-    description: 'Gitea token for posting the review'
+    description: 'Token for posting the review'
    required: true
  reviewer-name:
    description: 'Display name for the reviewer'
@@ -112,45 +138,325 @@ runs:
      id: version
      shell: bash
      run: |
-        GITEA_URL="${{ inputs.gitea-url || github.server_url }}"
-        REPO="${{ inputs.repo || 'rodin/review-bot' }}"
+        set -euo pipefail
+
+        # --- Input Validation ---
+
+        # Determine the repo hosting review-bot releases (not the repo being reviewed)
+        ACTION_REPO="${{ inputs.action-repo }}"
+        if [ -z "$ACTION_REPO" ]; then
+          # github.action_repository is the repo containing the running action
+          ACTION_REPO="${{ github.action_repository }}"
+        fi
+        if [ -z "$ACTION_REPO" ]; then
+          # Final fallback for Gitea (which may not set action_repository)
+          ACTION_REPO="rodin/review-bot"
+          echo "::notice::action-repo not specified and github.action_repository is empty; falling back to rodin/review-bot"
+        fi
+
+        # Validate ACTION_REPO matches owner/repo pattern (prevent path traversal)
+        if ! printf '%s' "$ACTION_REPO" | grep -qE '^[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+$'; then
+          echo "Error: action-repo '${ACTION_REPO}' does not match expected owner/repo format" >&2
+          exit 1
+        fi
+
+        # Detect VCS host type using github.api_url context.
+        # github.api_url is set on GitHub.com (https://api.github.com) and GHES
+        # (https://<host>/api/v3). It is empty/unset on Gitea Actions runners.
+        GITHUB_API_URL="${{ github.api_url }}"
+        if [ -n "$GITHUB_API_URL" ]; then
+          VCS_TYPE="github"
+        else
+          VCS_TYPE="gitea"
+        fi
+
+        # Determine SERVER_URL based on VCS type.
+        # SECURITY: On GitHub/GHES, ALWAYS use github.server_url — never trust
+        # inputs.vcs-url to prevent token exfiltration to attacker-controlled hosts.
+        if [ "$VCS_TYPE" = "github" ]; then
+          SERVER_URL="${{ github.server_url }}"
+          if [ -n "${{ inputs.vcs-url }}" ]; then
+            echo "::warning::inputs.vcs-url is ignored on GitHub/GHES runners (VCS_TYPE=github). Using github.server_url instead."
+          fi
+        else
+          SERVER_URL="${{ inputs.vcs-url || github.server_url }}"
+        fi
+        # Strip trailing slash if present
+        SERVER_URL="${SERVER_URL%/}"
+
+        # Validate SERVER_URL for Gitea path: must be https, no whitespace/newlines.
+        # The [^[:space:]] class already rejects newlines, so no separate newline check needed.
+        if [ "$VCS_TYPE" = "gitea" ]; then
+          if ! printf '%s' "$SERVER_URL" | grep -qE '^https://[^[:space:]]+$'; then
+            echo "Error: SERVER_URL '${SERVER_URL}' must be an https:// URL with no whitespace" >&2
+            exit 1
+          fi
+
+          # Additional IP-level SSRF defense: resolve the hostname and reject
+          # requests to RFC1918, RFC6598 (carrier-grade NAT), loopback, link-local,
+          # and other reserved addresses.
+          # python3 is required on ubuntu-* runners (see requirements comment above).
+          # Use printf to write the script to a temp file so the python lines are valid
+          # YAML (each indented line becomes a printf argument — no unindented code).
+          # SERVER_URL is passed via CHECK_URL env var, never interpolated into python code.
+          printf '%s\n' \
+            'import socket,ipaddress,sys,os' \
+            'from urllib.parse import urlparse' \
+            'u=os.environ["CHECK_URL"]; parsed=urlparse(u)' \
+            'if parsed.username or parsed.password:' \
+            '  print("Error: URL contains user-info — not allowed",file=sys.stderr); sys.exit(2)' \
+            'h=parsed.hostname' \
+            '(print("Error: no hostname",file=sys.stderr) or sys.exit(2)) if not h else None' \
+            'try: rs=socket.getaddrinfo(h,None)' \
+            'except socket.gaierror as e: print(f"DNS error: {e}",file=sys.stderr); sys.exit(1)' \
+            'if not rs: print("Error: no addresses",file=sys.stderr); sys.exit(1)' \
+            'for _,_,_,_,(a,*_) in rs:' \
+            '  ip=ipaddress.ip_address(a)' \
+            '  if isinstance(ip,ipaddress.IPv6Address) and ip.ipv4_mapped: ip=ip.ipv4_mapped' \
+            '  cgn=ipaddress.ip_network("100.64.0.0/10")' \
+            '  if ip.is_private or ip.is_loopback or ip.is_link_local or ip.is_multicast or ip.is_reserved or ip in cgn:' \
+            '    print(f"blocked: {a}",file=sys.stderr); sys.exit(1)' \
+            > /tmp/_ssrf_check.py
+          CHECK_URL="${SERVER_URL}" python3 /tmp/_ssrf_check.py || {
+            echo "Error: SERVER_URL '${SERVER_URL}' resolves to a private/reserved IP address" >&2
+            exit 1
+          }
+        fi
+
+        # Determine auth token for release API requests
+        ACTION_TOKEN="${{ inputs.action-repo-token }}"
+        if [ -z "$ACTION_TOKEN" ]; then
+          if [ "$VCS_TYPE" = "github" ]; then
+            ACTION_TOKEN="${{ github.token }}"
+          else
+            ACTION_TOKEN="${{ inputs.reviewer-token }}"
+          fi
+        fi
+
+        # Validate token contains no control characters (defense-in-depth against header injection)
+        if [ -n "$ACTION_TOKEN" ]; then
+          if printf '%s' "$ACTION_TOKEN" | LC_ALL=C grep -q '[^[:print:]]'; then
+            echo "Error: ACTION_TOKEN contains control characters" >&2
+            exit 1
+          fi
+        fi
+
        if [ "${{ inputs.version }}" = "latest" ]; then
-          VERSION=$(curl -sSf "${GITEA_URL}/api/v1/repos/${REPO}/releases?limit=1" \
-            | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
+          if [ "$VCS_TYPE" = "github" ]; then
+            # SECURITY: Use github.api_url which is a trusted platform-provided value.
+            # Never construct API URLs from user-supplied inputs on GitHub.
+            API_URL="${GITHUB_API_URL}/repos/${ACTION_REPO}/releases?per_page=1"
+          else
+            # Gitea API — SERVER_URL was validated above
+            API_URL="${SERVER_URL}/api/v1/repos/${ACTION_REPO}/releases?limit=1"
+          fi
+
+          # Fetch latest version with inline auth header (no intermediate variable)
+          if [ -n "$ACTION_TOKEN" ]; then
+            if [ "$VCS_TYPE" = "github" ]; then
+              VERSION=$(curl -sSf --connect-timeout 10 --max-time 30 \
+                -H "Authorization: Bearer ${ACTION_TOKEN}" "$API_URL" \
+                | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
+            else
+              VERSION=$(curl -sSf --connect-timeout 10 --max-time 30 \
+                -H "Authorization: token ${ACTION_TOKEN}" "$API_URL" \
+                | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
+            fi
+          else
+            VERSION=$(curl -sSf --connect-timeout 10 --max-time 30 "$API_URL" \
+              | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
+          fi
+
          if [ -z "$VERSION" ]; then
-            echo "Failed to determine latest version" >&2
+            echo "Failed to determine latest version from ${API_URL}" >&2
            exit 1
          fi
        else
          VERSION="${{ inputs.version }}"
        fi
+
+        # Validate VERSION: no slashes or whitespace (prevent path traversal).
+        # [:space:] includes newlines and carriage returns in POSIX.
+        if printf '%s' "$VERSION" | grep -qE '[/[:space:]]'; then
+          echo "Error: VERSION '${VERSION}' contains invalid characters (newline, slash, or whitespace)" >&2
+          exit 1
+        fi
+
+        # Detect OS and architecture for platform-specific binary download
+        OS_RAW=$(uname -s | tr '[:upper:]' '[:lower:]')
+        case "$OS_RAW" in
+          linux)  OS="linux" ;;
+          darwin) OS="darwin" ;;
+          *)
+            echo "Error: unsupported OS: $(uname -s)" >&2
+            exit 1
+            ;;
+        esac
+
+        RAW_ARCH=$(uname -m)
+        case "$RAW_ARCH" in
+          x86_64)           ARCH="amd64" ;;
+          aarch64 | arm64)  ARCH="arm64" ;;
+          *)
+            echo "Error: unsupported architecture: $RAW_ARCH" >&2
+            exit 1
+            ;;
+        esac
+
        echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+        echo "os=${OS}" >> "$GITHUB_OUTPUT"
+        echo "arch=${ARCH}" >> "$GITHUB_OUTPUT"
+        echo "action_repo=${ACTION_REPO}" >> "$GITHUB_OUTPUT"
+        echo "server_url=${SERVER_URL}" >> "$GITHUB_OUTPUT"
+        echo "vcs_type=${VCS_TYPE}" >> "$GITHUB_OUTPUT"
+
+        # SECURITY: Pass token via masked environment variable instead of step output.
+        # Step outputs can leak in debug logs; GITHUB_ENV with masking is safer.
+        if [ -n "$ACTION_TOKEN" ]; then
+          echo "::add-mask::${ACTION_TOKEN}"
+          echo "ACTION_TOKEN=${ACTION_TOKEN}" >> "$GITHUB_ENV"
+        fi

    - name: Cache review-bot binary
      id: cache
      uses: actions/cache@v4
      with:
        path: ${{ runner.temp }}/review-bot
-        key: review-bot-linux-amd64-${{ steps.version.outputs.version }}
+        key: review-bot-${{ steps.version.outputs.os }}-${{ steps.version.outputs.arch }}-${{ steps.version.outputs.version }}

    - name: Install review-bot
      if: steps.cache.outputs.cache-hit != 'true'
      shell: bash
      run: |
-        GITEA_URL="${{ inputs.gitea-url || github.server_url }}"
-        REPO="${{ inputs.repo || 'rodin/review-bot' }}"
-        VERSION="${{ steps.version.outputs.version }}"
-        BINARY="review-bot-linux-amd64"
+        set -euo pipefail

-        curl -sSfL "${GITEA_URL}/${REPO}/releases/download/${VERSION}/${BINARY}" \
-          -o "${{ runner.temp }}/review-bot"
-        curl -sSfL "${GITEA_URL}/${REPO}/releases/download/${VERSION}/checksums.txt" \
-          -o "${{ runner.temp }}/checksums.txt"
+        SERVER_URL="${{ steps.version.outputs.server_url }}"
+        ACTION_REPO="${{ steps.version.outputs.action_repo }}"
+        VERSION="${{ steps.version.outputs.version }}"
+        VCS_TYPE="${{ steps.version.outputs.vcs_type }}"
+        OS="${{ steps.version.outputs.os }}"
+        ARCH="${{ steps.version.outputs.arch }}"
+        # Read token from masked environment variable (set in Determine version step)
+        # Falls back to empty if not set (public repos don't need auth)
+        ACTION_TOKEN="${ACTION_TOKEN:-}"
+        BINARY="review-bot-${OS}-${ARCH}"
+
+        # SECURITY: Re-validate SERVER_URL at the start of this step to mitigate DNS
+        # rebinding attacks. A DNS TTL expiry between "Determine version" and here
+        # could allow an attacker to change the resolved IP to a private/reserved
+        # address, causing curl to send ACTION_TOKEN to an internal host.
+        # Only needed on Gitea path (VCS_TYPE=gitea); GitHub/GHES uses platform-controlled URLs.
+        if [ "$VCS_TYPE" = "gitea" ]; then
+          printf '%s\n' \
+            'import socket,ipaddress,sys,os' \
+            'from urllib.parse import urlparse' \
+            'u=os.environ["CHECK_URL"]; parsed=urlparse(u)' \
+            'if parsed.username or parsed.password:' \
+            '  print("Error: URL contains user-info — not allowed",file=sys.stderr); sys.exit(2)' \
+            'h=parsed.hostname' \
+            '(print("Error: no hostname",file=sys.stderr) or sys.exit(2)) if not h else None' \
+            'try: rs=socket.getaddrinfo(h,None)' \
+            'except socket.gaierror as e: print(f"DNS error: {e}",file=sys.stderr); sys.exit(1)' \
+            'if not rs: print("Error: no addresses",file=sys.stderr); sys.exit(1)' \
+            'for _,_,_,_,(a,*_) in rs:' \
+            '  ip=ipaddress.ip_address(a)' \
+            '  if isinstance(ip,ipaddress.IPv6Address) and ip.ipv4_mapped: ip=ip.ipv4_mapped' \
+            '  cgn=ipaddress.ip_network("100.64.0.0/10")' \
+            '  if ip.is_private or ip.is_loopback or ip.is_link_local or ip.is_multicast or ip.is_reserved or ip in cgn:' \
+            '    print(f"blocked: {a}",file=sys.stderr); sys.exit(1)' \
+              > /tmp/_ssrf_check_install.py
+          CHECK_URL="${SERVER_URL}" python3 /tmp/_ssrf_check_install.py || {
+            echo "Error: SERVER_URL '${SERVER_URL}' resolves to a private/reserved IP address" >&2
+            exit 1
+          }
+        fi
+
+        if [ "$VCS_TYPE" = "github" ]; then
+          # GitHub/GHES: Use REST API for release asset downloads.
+          # Web release URLs ({server}/.../releases/download/{tag}/{asset}) redirect
+          # to S3 and don't reliably support Authorization headers for private repos.
+          # The REST API endpoint with Accept: application/octet-stream is required.
+          # GITHUB_API_URL: trusted platform value, same as detected in "Determine version" step.
+          GITHUB_API_URL="${{ github.api_url }}"
+
+          if [ -n "$ACTION_TOKEN" ]; then
+            RELEASE_JSON=$(curl -sSf --connect-timeout 10 --max-time 30 \
+              -H "Authorization: Bearer ${ACTION_TOKEN}" \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/tags/${VERSION}")
+          else
+            RELEASE_JSON=$(curl -sSf --connect-timeout 10 --max-time 30 \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/tags/${VERSION}")
+          fi
+
+          # Extract asset IDs for binary and checksums
+          BINARY_ASSET_ID=$(printf '%s' "$RELEASE_JSON" | python3 -c "import sys, json; assets = json.load(sys.stdin).get('assets', []); matches = [a['id'] for a in assets if a['name'] == '${BINARY}']; print(matches[0] if matches else '')")
+          if [ -z "$BINARY_ASSET_ID" ]; then
+            echo "Error: could not find asset '${BINARY}' in release ${VERSION}" >&2
+            exit 1
+          fi
+
+          CHECKSUMS_ASSET_ID=$(printf '%s' "$RELEASE_JSON" | python3 -c "import sys, json; assets = json.load(sys.stdin).get('assets', []); matches = [a['id'] for a in assets if a['name'] == 'checksums.txt']; print(matches[0] if matches else '')")
+          if [ -z "$CHECKSUMS_ASSET_ID" ]; then
+            echo "Error: could not find asset 'checksums.txt' in release ${VERSION}" >&2
+            exit 1
+          fi
+
+          # Download assets via REST API with Accept: application/octet-stream
+          if [ -n "$ACTION_TOKEN" ]; then
+            curl -sSfL --connect-timeout 10 --max-time 120 \
+              -H "Authorization: Bearer ${ACTION_TOKEN}" \
+              -H "Accept: application/octet-stream" \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/assets/${BINARY_ASSET_ID}" \
+              -o "${{ runner.temp }}/review-bot"
+            curl -sSfL --connect-timeout 10 --max-time 30 \
+              -H "Authorization: Bearer ${ACTION_TOKEN}" \
+              -H "Accept: application/octet-stream" \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/assets/${CHECKSUMS_ASSET_ID}" \
+              -o "${{ runner.temp }}/checksums.txt"
+          else
+            curl -sSfL --connect-timeout 10 --max-time 120 \
+              -H "Accept: application/octet-stream" \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/assets/${BINARY_ASSET_ID}" \
+              -o "${{ runner.temp }}/review-bot"
+            curl -sSfL --connect-timeout 10 --max-time 30 \
+              -H "Accept: application/octet-stream" \
+              "${GITHUB_API_URL}/repos/${ACTION_REPO}/releases/assets/${CHECKSUMS_ASSET_ID}" \
+              -o "${{ runner.temp }}/checksums.txt"
+          fi
+        else
+          # Gitea: Direct download via web release URLs (Gitea serves assets
+          # directly without redirects — no -L needed).
+          # SECURITY: Omitting -L prevents forwarding Authorization header to
+          # unexpected hosts if Gitea ever introduces CDN redirects.
+          DOWNLOAD_URL="${SERVER_URL}/${ACTION_REPO}/releases/download/${VERSION}"
+
+          if [ -n "$ACTION_TOKEN" ]; then
+            curl -sSf --connect-timeout 10 --max-time 120 \
+              -H "Authorization: token ${ACTION_TOKEN}" \
+              "${DOWNLOAD_URL}/${BINARY}" -o "${{ runner.temp }}/review-bot"
+            curl -sSf --connect-timeout 10 --max-time 30 \
+              -H "Authorization: token ${ACTION_TOKEN}" \
+              "${DOWNLOAD_URL}/checksums.txt" -o "${{ runner.temp }}/checksums.txt"
+          else
+            curl -sSf --connect-timeout 10 --max-time 120 \
+              "${DOWNLOAD_URL}/${BINARY}" -o "${{ runner.temp }}/review-bot"
+            curl -sSf --connect-timeout 10 --max-time 30 \
+              "${DOWNLOAD_URL}/checksums.txt" -o "${{ runner.temp }}/checksums.txt"
+          fi
+        fi

        # Verify SHA-256 checksum
+        # NOTE: This verifies integrity (download wasn't corrupted) but not
+        # authenticity — both binary and checksums come from the same server.
+        # For stronger guarantees, consider GPG signature verification.
        cd "${{ runner.temp }}"
-        EXPECTED=$(grep "${BINARY}" checksums.txt | awk '{print $1}')
-        ACTUAL=$(sha256sum review-bot | awk '{print $1}')
+        EXPECTED=$(grep -E "^[0-9a-f]+[[:space:]]+\*?${BINARY}$" checksums.txt | awk '{print $1}')
+        # sha256sum (GNU) is not available on macOS; use shasum -a 256 on darwin.
+        if [ "${OS}" = "darwin" ]; then
+          ACTUAL=$(shasum -a 256 review-bot | awk '{print $1}')
+        else
+          ACTUAL=$(sha256sum review-bot | awk '{print $1}')
+        fi

        if [ -z "$EXPECTED" ]; then
          echo "Error: no checksum found for ${BINARY}" >&2
@@ -164,12 +470,12 @@ runs:
        fi

        chmod +x "${{ runner.temp }}/review-bot"
-        echo "Installed review-bot ${VERSION} (checksum verified)"
+        echo "Installed review-bot-${OS}-${ARCH} ${VERSION} (checksum verified)"

    - name: Run review
      shell: bash
      env:
-        GITEA_URL: ${{ inputs.gitea-url || github.server_url }}
+        VCS_URL: ${{ steps.version.outputs.server_url }}
        GITEA_REPO: ${{ inputs.repo || github.repository }}
        PR_NUMBER: ${{ inputs.pr-number || github.event.pull_request.number }}
        REVIEWER_TOKEN: ${{ inputs.reviewer-token }}
@@ -49,7 +49,7 @@ jobs:
      - run: go build -o review-bot ./cmd/review-bot
      - name: Run ${{ matrix.name }} review
        env:
-          GITEA_URL: ${{ github.server_url }}
+          VCS_URL: ${{ github.server_url }}
          GITEA_REPO: ${{ github.repository }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          REVIEWER_TOKEN: ${{ secrets[matrix.token_secret] }}
@@ -0,0 +1,175 @@
+# Plan: Issue #125 — Rename GITEA_URL → VCS_URL
+
+## Problem
+
+The `GITEA_URL` environment variable (and `--gitea-url` flag) implies the binary only works with Gitea.
+Now that review-bot supports both Gitea and GitHub/GHES, this name is misleading.
+Renaming to `VCS_URL` makes the binary platform-agnostic in its interface.
+
+## Constraints
+
+- Must not break existing users who already use `GITEA_URL` — need a fallback
+- The CLI flag `--gitea-url` should also be updated to `--vcs-url` for consistency
+- `INTEGRATION_GITEA_URL` in integration tests is a test-only env var, not the binary's interface; but should be updated for clarity
+- The action YAML uses `GITEA_URL` as an internal shell variable in bash scripts — distinct from the env var passed to the binary
+- All changes must compile and pass existing tests
+
+## Files Affected
+
+### Binary / Go source
+| File | Change |
+|------|--------|
+| `cmd/review-bot/main.go` | Rename `--gitea-url` → `--vcs-url`, add `VCS_URL` as primary, keep `GITEA_URL` fallback |
+| `cmd/review-bot/integration_test.go` | Rename `INTEGRATION_GITEA_URL` → `INTEGRATION_VCS_URL` (test-only, no external compat concern) |
+| `integration_test.go` | Same — rename `INTEGRATION_GITEA_URL` → `INTEGRATION_VCS_URL` |
+
+### Action YAML
+| File | Change |
+|------|--------|
+| `.gitea/actions/review/action.yml` | Rename input `gitea-url` → `vcs-url`; update env var passed to binary: `VCS_URL` instead of `GITEA_URL`; keep internal bash var as `GITEA_URL` (only used for release download, not passed to binary) |
+| `.gitea/workflows/ci.yml` | Rename `GITEA_URL` env var to `VCS_URL` in Run review step |
+
+### Documentation
+| File | Change |
+|------|--------|
+| `README.md` | Update CLI example, env var table entry |
+
+## Proposed Approach
+
+### 1. Backward-compatible env var lookup in main.go
+
+Replace:
+```go
+giteaURL := flag.String("gitea-url", envOrDefault("GITEA_URL", ""), "Gitea instance URL")
+```
+
+With:
+```go
+giteaURL := flag.String("vcs-url", envOrDefaultFallback("VCS_URL", "GITEA_URL", ""), "VCS server URL (e.g. https://gitea.example.com)")
+```
+
+Add a helper:
+```go
+// envOrDefaultFallback reads primary env var; if empty, falls back to deprecated env var.
+func envOrDefaultFallback(primary, deprecated, defaultVal string) string {
+    if v := os.Getenv(primary); v != "" {
+        return v
+    }
+    if v := os.Getenv(deprecated); v != "" {
+        slog.Warn("deprecated env var in use; rename to " + primary, "old", deprecated, "new", primary)
+        return v
+    }
+    return defaultVal
+}
+```
+
+**Note:** This must be called AFTER `setupLogger` conceptually, but the flag default is evaluated at flag registration time. Since `setupLogger` runs before `flag.Parse()`, the slog.Warn will print correctly at runtime. We use `log.Printf` as a fallback if this proves problematic.
+
+Actually — flag defaults are evaluated at registration (line 57), before `setupLogger`. The warning won't go through slog. Two options:
+- Use `log.Printf` for the deprecation warning (always visible)
+- Move the fallback lookup to after `flag.Parse()`, checking if the parsed value is still empty
+
+**Decision:** Move fallback to a post-parse check. This is cleaner:
+```go
+vcsURL := flag.String("vcs-url", os.Getenv("VCS_URL"), "VCS server URL")
+flag.Parse()
+// Backward compat: fall back to deprecated GITEA_URL
+if *vcsURL == "" {
+    if v := os.Getenv("GITEA_URL"); v != "" {
+        slog.Warn("GITEA_URL is deprecated; use VCS_URL instead")
+        *vcsURL = v
+    }
+}
+```
+
+This is clean, idiomatic, and the warning goes through slog correctly.
+
+### 2. Keep `--gitea-url` as deprecated alias
+
+Add a hidden flag for backward compat:
+```go
+giteaURLAlias := flag.String("gitea-url", "", "Deprecated: use --vcs-url")
+```
+
+Post-parse:
+```go
+if *vcsURL == "" && *giteaURLAlias != "" {
+    slog.Warn("--gitea-url is deprecated; use --vcs-url instead")
+    *vcsURL = *giteaURLAlias
+}
+```
+
+### 3. Internal variable rename
+
+Rename `giteaURL` local variable → `vcsURL` throughout `main.go` for consistency.
+
+### 4. Error message update
+
+```go
+fmt.Fprintf(os.Stderr, "Required: --vcs-url, --repo, --pr, --reviewer-token, --llm-model\n")
+```
+
+### 5. Action YAML changes
+
+In `.gitea/actions/review/action.yml`:
+- Input `gitea-url` → `vcs-url` (with same description, `required: false`, `default: ''`)
+- Line 172: `GITEA_URL: ${{ inputs.gitea-url || github.server_url }}` → `VCS_URL: ${{ inputs.vcs-url || github.server_url }}`
+- Lines 115, 140: internal bash vars `GITEA_URL=` are used for downloading binaries — NOT passed to the review-bot binary. Leave them as internal bash vars (they're scope-local in bash). These could be renamed to `SERVER_URL` or `BASE_URL` for local clarity, but renaming them isn't strictly required.
+
+In `.gitea/workflows/ci.yml`:
+- Line 52: `GITEA_URL: ${{ github.server_url }}` → `VCS_URL: ${{ github.server_url }}`
+
+### 6. Integration test updates
+
+`INTEGRATION_GITEA_URL` → `INTEGRATION_VCS_URL` in both test files.
+
+### 7. README
+
+- CLI example: `--gitea-url` → `--vcs-url`
+- Env var table: `GITEA_URL` → `VCS_URL`, add note about `GITEA_URL` fallback
+
+## Backward Compatibility Summary
+
+| Old | New | Fallback? |
+|-----|-----|-----------|
+| `GITEA_URL` env var | `VCS_URL` | ✅ with deprecation warning |
+| `--gitea-url` flag | `--vcs-url` | ✅ with deprecation warning |
+| `gitea-url` action input | `vcs-url` | ⚠️ No (action version bump handles this) |
+| `INTEGRATION_GITEA_URL` | `INTEGRATION_VCS_URL` | N/A (test-only) |
+
+## Error Cases
+
+- Both `VCS_URL` and `GITEA_URL` set: `VCS_URL` wins (primary takes precedence)
+- Both `--vcs-url` and `--gitea-url` provided: `--vcs-url` wins
+- Neither set: existing "missing required flags" error unchanged
+
+## Edge Cases
+
+- `os.Getenv` returns "" for unset AND set-to-empty — consistent with existing behavior
+- The `envOrDefault` helper is unchanged; we add `envOrDefaultFallback` for the one renamed var
+
+## Testing Strategy
+
+- Existing unit tests pass unchanged (they don't test env var parsing directly)
+- Integration tests updated to use new env var name
+- Manual: `GITEA_URL=https://example.com ./review-bot --repo x --pr 1 ...` should print deprecation warning and proceed
+- Manual: `VCS_URL=https://example.com ./review-bot ...` should work silently
+
+## Completion Checklist
+
+1. `VCS_URL` is read first; `GITEA_URL` is fallback with deprecation warning
+2. `--vcs-url` flag is primary; `--gitea-url` is deprecated alias with warning
+3. Error message references `--vcs-url` not `--gitea-url`
+4. `action.yml` passes `VCS_URL` (not `GITEA_URL`) to the binary
+5. `ci.yml` passes `VCS_URL` (not `GITEA_URL`) to the binary
+6. README updated in CLI example and env var table
+7. Integration tests use `INTEGRATION_VCS_URL`
+8. `go test ./...` passes
+9. `go vet ./...` passes
+10. `go build ./cmd/review-bot` succeeds
+
+## Open Questions
+
+- Should the CLI flag `--gitea-url` be completely hidden from `--help` or just deprecated with a note? The issue doesn't specify. Decision: keep it visible but add "(deprecated: use --vcs-url)" to the description.
+- Should action.yml also add `gitea-url` as a deprecated input alias? The issue says "Update the action to pass the new env var name" — no mention of backward compat for the action input. Decision: rename only, no alias (action users pin a version anyway).
+- The bash-internal `GITEA_URL` variable in action.yml scripts (used for release download, not passed to binary) — rename for clarity? Decision: yes, rename to `BASE_URL` to avoid confusion with the env var.
@@ -282,7 +282,7 @@ Rules:

 ```bash
 review-bot \
-  --gitea-url https://gitea.example.com \
+  --vcs-url https://gitea.example.com \
  --repo owner/name \
  --pr 42 \
  --reviewer-token "$GITEA_TOKEN" \
@@ -299,7 +299,7 @@ All flags have environment variable equivalents:

 | Flag | Env Var |
 |------|---------|
-| `--gitea-url` | `GITEA_URL` |
+| `--vcs-url` | `VCS_URL` (fallback: `GITEA_URL`) |
 | `--repo` | `GITEA_REPO` |
 | `--pr` | `PR_NUMBER` |
 | `--reviewer-token` | `REVIEWER_TOKEN` |
@@ -0,0 +1,151 @@
+## Dev Loop: review-bot — Continuous Health Monitor
+
+### Current Cycle: 2026-05-15 02:10 UTC ✅
+
+**Repository Status:** OPTIMAL
+- Main: `9f3f321` (clean, all tests pass)
+- Working tree: clean
+- Build: ✅ successful
+- Vet: ✅ clean
+- Test suite: ALL PASS
+
+---
+
+## Latest Delivered: Issue #130 ✅
+
+### GitHub API + VCS Routing Complete
+
+**Phase 1: GitHub API Methods** ✅
+- 12+ methods implemented in `github/client.go`
+- GetPullRequest, GetPullRequestDiff, GetPullRequestFiles
+- GetCommitStatuses, GetFileContent, ListContents, GetAllFilesInPath
+- PostReview, ListReviews, DeleteReview, GetAuthenticatedUser, RequestReviewer
+
+**Phase 2: VCS Abstraction** ✅
+- `vcsClient` interface (GitHub + Gitea)
+- `giteaExtClient` interface (Gitea-specific ops)
+- Adapters for both platforms
+- URL-based auto-detection (github.com → GitHub, else Gitea)
+- `--vcs-type` flag and `VCS_TYPE` env override
+
+**Quality Metrics** ✅
+- 474 lines of GitHub client tests
+- 82 lines of routing tests
+- 361 lines of VCS adapter code
+- Security review: APPROVED (MINOR: URL heuristic note)
+- All tests passing; go vet clean
+
+**Known Limitations** (Documented)
+- GitHub: Can only delete PENDING (draft) reviews, not submitted (handled gracefully)
+- GitHub pagination: per-page=100 with Link header checking
+- Check-runs: Uses statuses API; check-runs deferrable to future enhancement
+
+---
+
+## Repository Status Post-Merge
+
+### Main Branch
+- Commit: `9f3f321`
+- Status: ✅ All systems healthy
+
+### Recent Merged PRs
+| PR | Issue | Title | Status |
+|---|---|---|---|
+| #131 | #130 | GitHub API methods & VCS routing | ✅ MERGED |
+| #129 | #123 | IP-level SSRF defense | ✅ MERGED |
+| #128 | #125 | VCS_URL deprecation & renaming | ✅ MERGED |
+| #127 | #124 | Multi-arch binary support | ✅ MERGED |
+| #126 | #120 | GitHub Actions composite action | ✅ MERGED |
+
+### Closed Issues
+- #130, #123, #125, #124, #120
+
+### Open Issues
+- None blocking; backlog tracked in Gitea project board
+
+### Worktrees
+- All cleaned up; no stale branches
+
+---
+
+## Feature Completeness Summary
+
+### ✅ Core Functionality
+- Multi-provider LLM support (OpenAI, Anthropic, SAP AI Core)
+- Gitea PR review (mature, proven)
+- **NEW: GitHub PR review (fully implemented)**
+- VCS abstraction (Gitea/GitHub transparent routing)
+- SSRF defense with IP-level validation
+- Multi-architecture binary deployment
+
+### ✅ Review Quality
+- Structured reviews with code snippets
+- LLM-driven analysis
+- Persona-based customization
+- Context awareness
+
+### ✅ Security
+- RFC6598 CGN detection
+- HTTPS enforcement
+- Redirect safety
+- Credential handling (no logs, no reflection leaks)
+- URL validation for VCS API access
+
+---
+
+## Next Phase: Backlog Priorities
+
+### Priority 1: PR Submission
+**Issue:** #132+ (create)
+**Goal:** Enable review-bot to create PRs (not just post reviews)
+**Scope:** PR creation flow, commit logic, test coverage
+**Est. Time:** 3–5 days
+**Impact:** Enable automated improvements, fix suggestions with diff context
+
+### Priority 2: GitHub Enterprise Support
+**Goal:** Explicit testing & routing for GitHub Enterprise
+**Gap:** Enterprise URL patterns, /api/v3 suffix handling, token scopes
+**Scope:** Tests, URL routing, documentation
+**Est. Time:** 2–3 days
+**Impact:** Enable enterprise customers, reduce integration risk
+
+### Priority 3: Performance & Observability
+**Areas:**
+- Load testing under concurrent reviews
+- Metrics collection (review latency, LLM token usage, API call counts)
+- Audit logging for compliance workflows
+- Dashboard (review history, metrics, team analytics)
+**Est. Time:** 5–7 days
+**Impact:** Operational confidence, troubleshooting, compliance
+
+### Priority 4: Enhanced Context
+**Opportunities:**
+- Semantic code understanding (AST-based analysis for specific languages)
+- Project-specific review rules (.review-bot.yaml in repo root)
+- Team-level customization
+**Est. Time:** 7–10 days
+
+---
+
+## Dev Loop Schedule
+
+- **Interval:** 4 hours
+- **Next check:** ~6:10 AM UTC (May 15)
+- **Health:** ✅ Optimal — all systems running
+- **Status:** Ready for next phase work
+
+---
+
+## Metadata
+
+| Key | Value |
+|---|---|
+| Repo | `/home/ubuntu/review-bot` |
+| Main SHA | `9f3f321` |
+| Last update | 2026-05-15 02:10 UTC |
+| Status | All systems optimal |
+| Next phase | PR submission or GitHub Enterprise support |
+
+---
+
+**Summary:** review-bot now supports both GitHub and Gitea PR reviews with a unified abstraction layer. All tests pass, code is clean, security is approved. Ready to move to PR submission or GitHub Enterprise support in the next cycle.
@@ -10,6 +10,7 @@ import (
 	"testing"

 	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/github"
 	"gitea.weiker.me/rodin/review-bot/llm"
 	"gitea.weiker.me/rodin/review-bot/review"
 )
@@ -17,7 +18,7 @@ import (
 // Integration test requires a running Gitea instance and LLM endpoint.
 // Set environment variables:
 //
-//	INTEGRATION_GITEA_URL     - Gitea base URL
+//	INTEGRATION_VCS_URL       - VCS base URL
 //	INTEGRATION_GITEA_TOKEN   - Gitea API token with repo access
 //	INTEGRATION_GITEA_REPO    - owner/repo with an open PR
 //	INTEGRATION_PR_NUMBER     - PR number to test against
@@ -25,7 +26,7 @@ import (
 //	INTEGRATION_LLM_API_KEY   - LLM API key
 //	INTEGRATION_LLM_MODEL     - Model name
 func TestIntegration_FullReviewFlow(t *testing.T) {
-	giteaURL := os.Getenv("INTEGRATION_GITEA_URL")
+	giteaURL := os.Getenv("INTEGRATION_VCS_URL")
 	giteaToken := os.Getenv("INTEGRATION_GITEA_TOKEN")
 	giteaRepo := os.Getenv("INTEGRATION_GITEA_REPO")
 	prNumStr := os.Getenv("INTEGRATION_PR_NUMBER")
@@ -104,7 +105,7 @@ func TestIntegration_FullReviewFlow(t *testing.T) {
 }

 func TestIntegration_PostAndCleanup(t *testing.T) {
-	giteaURL := os.Getenv("INTEGRATION_GITEA_URL")
+	giteaURL := os.Getenv("INTEGRATION_VCS_URL")
 	giteaToken := os.Getenv("INTEGRATION_GITEA_TOKEN")
 	giteaRepo := os.Getenv("INTEGRATION_GITEA_REPO")
 	prNumStr := os.Getenv("INTEGRATION_PR_NUMBER")
@@ -130,7 +131,7 @@ func TestIntegration_PostAndCleanup(t *testing.T) {
 	// Post a test review
 	sentinel := "<!-- review-bot:integration-test -->"
 	testBody := "# Integration Test Review\n\nThis is a test review.\n\n" + sentinel
-	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, "COMMENT", testBody, nil)
+	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, "COMMENT", testBody, "", nil)
 	if err != nil {
 		t.Fatalf("PostReview: %v", err)
 	}
@@ -159,3 +160,85 @@ func TestIntegration_PostAndCleanup(t *testing.T) {
 		t.Logf("Warning: could not delete test review %d: %v", posted.ID, err)
 	}
 }
+
+// TestIntegration_GitHub_PostAndVerifyReview exercises the full VCS routing path
+// for GitHub when INTEGRATION_GITHUB_TOKEN and INTEGRATION_GITHUB_REPO are set.
+// It verifies that the GitHub adapter is selected via VCS_TYPE=github and that
+// PostReview succeeds against a real GitHub PR.
+//
+// Required environment variables:
+//
+//	INTEGRATION_GITHUB_TOKEN  - GitHub personal access token with repo access
+//	INTEGRATION_GITHUB_REPO   - owner/repo with an open PR (e.g. Rodin-AI/review-bot)
+//	INTEGRATION_GITHUB_PR     - PR number to test against
+//
+// The test skips gracefully when these variables are absent.
+func TestIntegration_GitHub_PostAndVerifyReview(t *testing.T) {
+	githubToken := os.Getenv("INTEGRATION_GITHUB_TOKEN")
+	githubRepo := os.Getenv("INTEGRATION_GITHUB_REPO")
+	prNumStr := os.Getenv("INTEGRATION_GITHUB_PR")
+
+	if githubToken == "" || githubRepo == "" || prNumStr == "" {
+		t.Skip("INTEGRATION_GITHUB_TOKEN, INTEGRATION_GITHUB_REPO, and INTEGRATION_GITHUB_PR not set, skipping")
+	}
+
+	prNumber, err := strconv.Atoi(prNumStr)
+	if err != nil {
+		t.Fatalf("Invalid PR number %q: %v", prNumStr, err)
+	}
+
+	parts := strings.SplitN(githubRepo, "/", 2)
+	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
+		t.Fatalf("Invalid repo format %q, expected owner/repo", githubRepo)
+	}
+	owner, repoName := parts[0], parts[1]
+
+	ctx := context.Background()
+	ghClient := github.NewClient(githubToken, "https://api.github.com")
+
+	// Verify adapter selection: GetAuthenticatedUser must succeed.
+	user, err := ghClient.GetAuthenticatedUser(ctx)
+	if err != nil {
+		t.Fatalf("GetAuthenticatedUser: %v — check INTEGRATION_GITHUB_TOKEN", err)
+	}
+	t.Logf("Authenticated as: %s", user)
+
+	// Verify PR is accessible via GitHub adapter.
+	pr, err := ghClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	if err != nil {
+		t.Fatalf("GetPullRequest: %v", err)
+	}
+	t.Logf("PR: %s (sha: %s)", pr.Title, pr.Head.Sha)
+
+	// Post a COMMENT review — does not require PR approval permissions.
+	sentinel := "<!-- review-bot:integration-test -->"
+	testBody := "# Integration Test Review (GitHub)\n\nThis is an automated integration test.\n\n" + sentinel
+	posted, err := ghClient.PostReview(ctx, owner, repoName, prNumber, "COMMENT", testBody, "", nil)
+	if err != nil {
+		t.Fatalf("PostReview: %v", err)
+	}
+	t.Logf("Posted review ID: %d", posted.ID)
+
+	// Verify the review appears in ListReviews.
+	reviews, err := ghClient.ListReviews(ctx, owner, repoName, prNumber)
+	if err != nil {
+		t.Fatalf("ListReviews: %v", err)
+	}
+	found := false
+	for _, r := range reviews {
+		if r.ID == posted.ID && strings.Contains(r.Body, sentinel) {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("posted review ID %d not found in ListReviews output", posted.ID)
+	}
+
+	// Attempt cleanup — GitHub does not allow deleting submitted reviews,
+	// so this is expected to fail with ErrCannotDeleteSubmittedReview (422).
+	// Log it as informational only.
+	if err := ghClient.DeleteReview(ctx, owner, repoName, prNumber, posted.ID); err != nil {
+		t.Logf("Note: DeleteReview returned (expected for submitted GitHub reviews): %v", err)
+	}
+}
@@ -4,6 +4,7 @@ import (
 	"context"
 	"flag"
 	"fmt"
+	"io"
 	"log/slog"
 	"os"
 	"path/filepath"
@@ -13,12 +14,20 @@ import (

 	"gitea.weiker.me/rodin/review-bot/budget"
 	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/github"
 	"gitea.weiker.me/rodin/review-bot/llm"
 	"gitea.weiker.me/rodin/review-bot/review"
 )

 var version = "dev"

+// outWriter and errWriter are the output and error writers for subcommands.
+// They are variables so tests can capture output.
+var (
+	outWriter io.Writer = os.Stdout
+	errWriter io.Writer = os.Stderr
+)
+
 // setupLogger configures the global slog default logger based on format and verbosity.
 func setupLogger(format, verbosity string) {
 	var level slog.Level
@@ -49,12 +58,22 @@ func setupLogger(format, verbosity string) {
 }

 func main() {
+	// Dispatch subcommands before flag parsing so they get their own args.
+	// e.g. `review-bot validate-url <url>`
+	if len(os.Args) > 1 {
+		switch os.Args[1] {
+		case "validate-url":
+			os.Exit(runValidateURL(os.Args[2:]))
+		}
+	}
+
 	versionFlag := flag.Bool("version", false, "Print version and exit")
 	// Logging flags
 	logFormat := flag.String("log-format", envOrDefault("LOG_FORMAT", "text"), "Log output format: text or json")
 	verbosity := flag.String("verbosity", envOrDefault("LOG_VERBOSITY", "info"), "Log verbosity: debug, info, warn, error")
 	// CLI flags
-	giteaURL := flag.String("gitea-url", envOrDefault("GITEA_URL", ""), "Gitea instance URL")
+	vcsURL := flag.String("vcs-url", os.Getenv("VCS_URL"), "VCS server URL (e.g. https://gitea.example.com)")
+	giteaURLAlias := flag.String("gitea-url", "", "Deprecated: use --vcs-url")
 	repo := flag.String("repo", envOrDefault("GITEA_REPO", ""), "Repository (owner/name)")
 	prNum := flag.String("pr", envOrDefault("PR_NUMBER", ""), "Pull request number")
 	reviewerName := flag.String("reviewer-name", envOrDefault("REVIEWER_NAME", ""), "Reviewer display name")
@@ -91,12 +110,24 @@ func main() {

 	slog.Info("review-bot starting", "version", version)

+	// Backward compatibility: fall back to deprecated env var / flag if VCS_URL / --vcs-url not set.
+	if *vcsURL == "" {
+		if v := os.Getenv("GITEA_URL"); v != "" {
+			slog.Warn("GITEA_URL is deprecated; rename the environment variable to VCS_URL")
+			*vcsURL = v
+		}
+	}
+	if *vcsURL == "" && *giteaURLAlias != "" {
+		slog.Warn("--gitea-url is deprecated; use --vcs-url instead")
+		*vcsURL = *giteaURLAlias
+	}
+
 	// Validate required fields
 	// For aicore provider, llm-base-url and llm-api-key are not required
 	isAICore := llm.Provider(*llmProvider) == llm.ProviderAICore
-	if *giteaURL == "" || *repo == "" || *prNum == "" || *reviewerToken == "" || *llmModel == "" {
+	if *vcsURL == "" || *repo == "" || *prNum == "" || *reviewerToken == "" || *llmModel == "" {
 		fmt.Fprintf(os.Stderr, "Error: missing required flags or environment variables\n\n")
-		fmt.Fprintf(os.Stderr, "Required: --gitea-url, --repo, --pr, --reviewer-token, --llm-model\n")
+		fmt.Fprintf(os.Stderr, "Required: --vcs-url, --repo, --pr, --reviewer-token, --llm-model\n")
 		os.Exit(1)
 	}
 	if !isAICore && (*llmBaseURL == "" || *llmAPIKey == "") {
@@ -139,7 +170,39 @@ func main() {
 	}

 	// Initialize clients
-	giteaClient := gitea.NewClient(*giteaURL, *reviewerToken)
+	// Detect VCS type: explicit flag > env var > URL heuristic (default: gitea).
+	vcsType := envOrDefault("VCS_TYPE", "")
+	if vcsType == "" {
+		// Heuristic: if the URL looks like github.com or a GitHub Enterprise host,
+		// default to GitHub. The composite action sets VCS_TYPE explicitly, so this
+		// is a fallback for manual invocations.
+		if strings.Contains(*vcsURL, "github.com") || strings.Contains(*vcsURL, "github.concur.com") {
+			vcsType = "github"
+		} else {
+			vcsType = "gitea"
+		}
+	}
+	slog.Info("VCS type detected", "vcs_type", vcsType, "vcs_url", *vcsURL)
+
+	var vcs vcsClient
+	switch vcsType {
+	case "github":
+		// GitHub: baseURL is the API URL, derived from server URL.
+		// github.com → https://api.github.com
+		// GHES (e.g. https://ghe.example.com) → https://ghe.example.com/api/v3
+		apiURL := githubAPIURL(*vcsURL)
+		ghClient := github.NewClient(*reviewerToken, apiURL)
+		vcs = newGithubVCSAdapter(ghClient)
+		slog.Info("using GitHub VCS client", "api_url", apiURL)
+	case "gitea":
+		giteaClient := gitea.NewClient(*vcsURL, *reviewerToken)
+		vcs = newGiteaVCSAdapter(giteaClient)
+		slog.Info("using Gitea VCS client", "url", *vcsURL)
+	default:
+		slog.Error("unsupported VCS type", "vcs_type", vcsType, "valid", "gitea, github")
+		os.Exit(1)
+	}
+
 	llmClient := llm.NewClient(*llmBaseURL, *llmAPIKey, *llmModel)
 	if *llmTemp < 0 || *llmTemp > 2 {
 		slog.Error("invalid LLM temperature", "temperature", *llmTemp, "range", "0-2")
@@ -177,7 +240,7 @@ func main() {
 	var persona *review.Persona
 	if *personaName != "" {
 		// Try loading from repo first, then fall back to built-in
-		repoPersonas, err := review.LoadRepoPersonas(ctx, newGiteaClientAdapter(giteaClient), owner, repoName)
+		repoPersonas, err := review.LoadRepoPersonas(ctx, vcs, owner, repoName)
 		if err != nil {
 			slog.Warn("could not load repo personas", "repo", owner+"/"+repoName, "error", err)
 			// Continue with built-in personas only.
@@ -213,7 +276,7 @@ func main() {
 	slog.Info("reviewing pull request", "pr", prNumber, "repo", fmt.Sprintf("%s/%s", owner, repoName))

 	// Step 1: Fetch PR metadata
-	pr, err := giteaClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	pr, err := vcs.GetPullRequest(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch PR", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -221,7 +284,7 @@ func main() {
 	slog.Info("fetched PR metadata", "pr", prNumber, "title", pr.Title)

 	// Step 2: Fetch diff
-	diff, err := giteaClient.GetPullRequestDiff(ctx, owner, repoName, prNumber)
+	diff, err := vcs.GetPullRequestDiff(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch diff", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -230,11 +293,11 @@ func main() {

 	// Step 3: Fetch full file content for modified files
 	fileContext := ""
-	files, err := giteaClient.GetPullRequestFiles(ctx, owner, repoName, prNumber)
+	files, err := vcs.GetPullRequestFiles(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Warn("could not fetch PR files list", "pr", prNumber, "error", err)
 	} else {
-		fileContext = fetchFileContext(ctx, giteaClient, owner, repoName, pr.Head.Ref, files)
+		fileContext = fetchFileContext(ctx, vcs, owner, repoName, pr.Head.Ref, files)
 		slog.Debug("fetched file context", "files", len(files))
 	}

@@ -242,7 +305,7 @@ func main() {
 	ciPassed := true
 	ciDetails := ""
 	if pr.Head.Sha != "" {
-		statuses, err := giteaClient.GetCommitStatuses(ctx, owner, repoName, pr.Head.Sha)
+		statuses, err := vcs.GetCommitStatuses(ctx, owner, repoName, pr.Head.Sha)
 		if err != nil {
 			slog.Warn("could not fetch CI status", "sha", pr.Head.Sha, "error", err)
 		} else {
@@ -254,7 +317,7 @@ func main() {
 	// Step 5: Load conventions file if specified
 	conventions := ""
 	if *conventionsFile != "" {
-		content, err := giteaClient.GetFileContent(ctx, owner, repoName, *conventionsFile)
+		content, err := vcs.GetFileContent(ctx, owner, repoName, *conventionsFile)
 		if err != nil {
 			slog.Warn("could not load conventions file", "file", *conventionsFile, "error", err)
 		} else {
@@ -266,7 +329,7 @@ func main() {
 	// Step 6: Load patterns from external repo if specified
 	patterns := ""
 	if *patternsRepo != "" {
-		patterns = fetchPatterns(ctx, giteaClient, *patternsRepo, *patternsFiles)
+		patterns = fetchPatterns(ctx, vcs, *patternsRepo, *patternsFiles)
 		slog.Debug("loaded patterns", "repo", *patternsRepo, "bytes", len(patterns))
 	}

@@ -381,7 +444,7 @@ func main() {
 	// Stale check: verify HEAD hasn't moved since we started
 	evaluatedSHA := pr.Head.Sha
 	var currentSHA string
-	currentPR, err := giteaClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	currentPR, err := vcs.GetPullRequest(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Warn("could not re-fetch PR for stale check", "pr", prNumber, "error", err)
 		// currentSHA stays empty — shouldSkipStaleReview will return false
@@ -398,10 +461,10 @@ func main() {

 	// Map findings to inline comments for lines present in the diff
 	diffRanges := gitea.ParseDiffNewLines(diff)
-	var inlineComments []gitea.ReviewComment
+	var inlineComments []vcsReviewComment
 	for _, f := range result.Findings {
 		if f.File != "" && f.Line > 0 && diffRanges.Contains(f.File, f.Line) {
-			inlineComments = append(inlineComments, gitea.ReviewComment{
+			inlineComments = append(inlineComments, vcsReviewComment{
 				Path:        f.File,
 				NewPosition: int64(f.Line),
 				Body:        fmt.Sprintf("**[%s]** %s", f.Severity, f.Finding),
@@ -416,9 +479,9 @@ func main() {
 	// 1. POST new review first (gets non-stale approval badge on HEAD)
 	// 2. Then supersede old review with link to the new one
 	// Order matters: post first so we have the new review's URL for the supersede message.
-	var oldReviews []gitea.Review
+	var oldReviews []vcsReview
 	if *reviewerName != "" {
-		existingReviews, err := giteaClient.ListReviews(ctx, owner, repoName, prNumber)
+		existingReviews, err := vcs.ListReviews(ctx, owner, repoName, prNumber)
 		if err != nil {
 			slog.Warn("could not list existing reviews", "pr", prNumber, "error", err)
 		} else {
@@ -431,11 +494,11 @@ func main() {
 	}

 	// Self-request as reviewer (ensures we appear in required-reviewer checks)
-	authUser, err := giteaClient.GetAuthenticatedUser(ctx)
+	authUser, err := vcs.GetAuthenticatedUser(ctx)
 	if err != nil {
 		slog.Warn("could not determine authenticated user for reviewer self-request", "error", err)
 	} else if authUser != "" {
-		if err := giteaClient.RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
+		if err := vcs.RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
 			slog.Warn("could not self-request as reviewer", "user", authUser, "error", err)
 		} else {
 			slog.Debug("self-requested as reviewer", "user", authUser, "pr", prNumber)
@@ -444,31 +507,34 @@ func main() {

 	// POST new review
 	slog.Info("posting review", "event", event, "pr", prNumber)
-	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, event, reviewBody, inlineComments)
+	posted, err := vcs.PostReview(ctx, owner, repoName, prNumber, event, reviewBody, evaluatedSHA, inlineComments)
 	if err != nil {
 		slog.Error("failed to post review", "pr", prNumber, "event", event, "error", err)
 		os.Exit(1)
 	}
 	slog.Info("review posted", "review_id", posted.ID, "user", posted.User.Login, "pr", prNumber)

-	// Supersede all old reviews with link to the new one
-	if len(oldReviews) > 0 {
-		newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(*giteaURL, "/"), owner, repoName, prNumber, posted.ID)
+	// Supersede all old reviews with link to the new one.
+	// This is only supported on Gitea (requires timeline API); GitHub reviews cannot
+	// be edited after submission, so we skip the supersede step there.
+	extVCS, isGiteaExt := vcs.(giteaExtClient)
+	if len(oldReviews) > 0 && isGiteaExt {
+		newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(*vcsURL, "/"), owner, repoName, prNumber, posted.ID)
 		for _, oldReview := range oldReviews {
-			cid, err := giteaClient.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, prNumber, oldReview.ID)
+			cid, err := extVCS.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, int64(prNumber), oldReview.ID)
 			if err != nil {
 				slog.Warn("could not find comment ID for old review", "review_id", oldReview.ID, "error", err)
 				continue
 			}
 			supersededBody := buildSupersededBody(oldReview.Body, oldReview.CommitID, newReviewURL, sentinel)
-			if err := giteaClient.EditComment(ctx, owner, repoName, cid, supersededBody); err != nil {
+			if err := extVCS.EditComment(ctx, owner, repoName, cid, supersededBody); err != nil {
 				slog.Warn("could not mark old review as superseded", "review_id", oldReview.ID, "comment_id", cid, "error", err)
 				continue
 			}
 			slog.Info("marked old review as superseded", "review_id", oldReview.ID, "new_review_id", posted.ID, "pr", prNumber)

 			// Resolve old review's inline comments
-			oldComments, err := giteaClient.ListReviewComments(ctx, owner, repoName, prNumber, oldReview.ID)
+			oldComments, err := extVCS.ListReviewComments(ctx, owner, repoName, int64(prNumber), oldReview.ID)
 			if err != nil {
 				slog.Warn("could not list old review comments for resolution", "review_id", oldReview.ID, "error", err)
 				continue
@@ -478,7 +544,7 @@ func main() {
 				if c.ID == 0 {
 					continue
 				}
-				if err := giteaClient.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
+				if err := extVCS.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
 					slog.Debug("could not resolve inline comment", "comment_id", c.ID, "error", err)
 					failed++
 				} else {
@@ -492,12 +558,14 @@ func main() {
 				slog.Warn("some inline comments could not be resolved", "review_id", oldReview.ID, "failed", failed, "pr", prNumber)
 			}
 		}
+	} else if len(oldReviews) > 0 {
+		slog.Info("skipping supersede of old reviews (not supported on this VCS)", "old_count", len(oldReviews), "pr", prNumber)
 	}

 }

 // fetchFileContext fetches the full content of modified files from the PR branch.
-func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, ref string, files []gitea.ChangedFile) string {
+func fetchFileContext(ctx context.Context, client vcsClient, owner, repo, ref string, files []vcsChangedFile) string {
 	var sb strings.Builder
 	for _, f := range files {
 		if ctx.Err() != nil {
@@ -524,7 +592,7 @@ func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, re
 // patternsFiles is comma-separated list of file paths or directories.
 // If a path ends with / or is a directory, all files within it are fetched recursively.
 // If patternsFiles is empty, all files from the repo root are fetched.
-func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patternsFiles string) string {
+func fetchPatterns(ctx context.Context, client vcsClient, patternsRepo, patternsFiles string) string {
 	var sb strings.Builder

 	repos := strings.Split(patternsRepo, ",")
@@ -601,7 +669,7 @@ func isPatternFile(path string) bool {
 }

 // evaluateCIStatus checks if all CI statuses indicate success.
-func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details string) {
+func evaluateCIStatus(statuses []vcsCommitStatus) (passed bool, details string) {
 	if len(statuses) == 0 {
 		return true, "no CI statuses found"
 	}
@@ -624,6 +692,19 @@ func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details strin
 	return true, "all checks passed"
 }

+// githubAPIURL converts a GitHub server URL to its API base URL.
+// github.com → https://api.github.com
+// GHES (e.g. https://ghe.example.com) → https://ghe.example.com/api/v3
+func githubAPIURL(serverURL string) string {
+	const canonicalGitHub = "https://github.com"
+	const githubAPIBase = "https://api.github.com"
+	if serverURL == "" || strings.TrimRight(serverURL, "/") == canonicalGitHub {
+		return githubAPIBase
+	}
+	// GitHub Enterprise Server: /api/v3 suffix
+	return strings.TrimRight(serverURL, "/") + "/api/v3"
+}
+
 func envOrDefault(key, defaultVal string) string {
 	if v := os.Getenv(key); v != "" {
 		return v
@@ -739,7 +820,7 @@ func buildSupersededBody(originalBody, commitSHA, newReviewURL, sentinel string)
 // Gitea user. This indicates misconfiguration where two roles share a token
 // instead of having separate Gitea accounts. Returns true if shared token
 // detected (caller should skip update-in-place logic to avoid clobbering).
-func hasSharedToken(reviews []gitea.Review, ownSentinel string) bool {
+func hasSharedToken(reviews []vcsReview, ownSentinel string) bool {
 	ownLogin := ""
 	for _, r := range reviews {
 		if strings.Contains(r.Body, ownSentinel) {
@@ -777,8 +858,8 @@ func extractSentinelName(body string) string {
 }

 // findOwnReview locates the most recent non-superseded review matching the sentinel.
-func findOwnReview(reviews []gitea.Review, sentinel string) *gitea.Review {
-	var best *gitea.Review
+func findOwnReview(reviews []vcsReview, sentinel string) *vcsReview {
+	var best *vcsReview
 	for i := range reviews {
 		if !strings.Contains(reviews[i].Body, sentinel) {
 			continue
@@ -794,8 +875,8 @@ func findOwnReview(reviews []gitea.Review, sentinel string) *gitea.Review {
 }

 // findAllOwnReviews returns all non-superseded reviews matching the sentinel.
-func findAllOwnReviews(reviews []gitea.Review, sentinel string) []gitea.Review {
-	var result []gitea.Review
+func findAllOwnReviews(reviews []vcsReview, sentinel string) []vcsReview {
+	var result []vcsReview
 	for i := range reviews {
 		if !strings.Contains(reviews[i].Body, sentinel) {
 			continue
@@ -821,31 +902,4 @@ func shouldSkipStaleReview(evaluatedSHA, currentSHA string) bool {
 	return evaluatedSHA != currentSHA
 }

-// giteaClientAdapter adapts gitea.Client to review.GiteaClient interface.
-type giteaClientAdapter struct {
-	client *gitea.Client
-}

-func newGiteaClientAdapter(c *gitea.Client) *giteaClientAdapter {
-	return &giteaClientAdapter{client: c}
-}
-
-func (a *giteaClientAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
-	entries, err := a.client.ListContents(ctx, owner, repo, path)
-	if err != nil {
-		return nil, err
-	}
-	result := make([]review.ContentEntry, len(entries))
-	for i, e := range entries {
-		result[i] = review.ContentEntry{
-			Name: e.Name,
-			Path: e.Path,
-			Type: e.Type,
-		}
-	}
-	return result, nil
-}
-
-func (a *giteaClientAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
-	return a.client.GetFileContent(ctx, owner, repo, filepath)
-}
@@ -10,7 +10,6 @@ import (
 	"strings"
 	"testing"

-	"gitea.weiker.me/rodin/review-bot/gitea"
 )

 func TestValidateReviewerName(t *testing.T) {
@@ -154,12 +153,11 @@ func TestValidateWorkspacePath(t *testing.T) {
 	}
 }

-func makeReview(id int64, login, state string, stale bool, body string) gitea.Review {
-	r := gitea.Review{
+func makeReview(id int64, login, state string, _ bool, body string) vcsReview {
+	r := vcsReview{
 		ID:    id,
 		Body:  body,
 		State: state,
-		Stale: stale,
 	}
 	r.User.Login = login
 	return r
@@ -216,7 +214,7 @@ func TestBuildSupersededBodyShortSHA(t *testing.T) {
 func TestFindOwnReview(t *testing.T) {
 	tests := []struct {
 		name     string
-		reviews  []gitea.Review
+		reviews  []vcsReview
 		sentinel string
 		wantID   int64
 		wantNil  bool
@@ -229,7 +227,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "found by sentinel",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(42, "bot", "APPROVED", false, "review body\n<!-- review-bot:sonnet -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -237,7 +235,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "wrong sentinel",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(42, "bot", "APPROVED", false, "body\n<!-- review-bot:gpt -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -245,7 +243,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "multiple reviews, returns first match",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "old\n<!-- review-bot:gpt -->"),
 				makeReview(20, "bot", "APPROVED", false, "new\n<!-- review-bot:sonnet -->"),
 			},
@@ -254,7 +252,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "skips superseded review",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "~~Original review~~\n\n**Superseded**\n<!-- review-bot:sonnet -->"),
 				makeReview(20, "bot", "APPROVED", false, "fresh review\n<!-- review-bot:sonnet -->"),
 			},
@@ -263,7 +261,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "only superseded reviews exist",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "~~Original review~~\n\n<!-- review-bot:sonnet -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -271,7 +269,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "picks highest ID among matches",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(50, "bot", "APPROVED", false, "v1\n<!-- review-bot:sonnet -->"),
 				makeReview(30, "bot", "APPROVED", false, "v0\n<!-- review-bot:sonnet -->"),
 			},
@@ -302,7 +300,7 @@ func TestFindOwnReview(t *testing.T) {
 func TestHasSharedToken(t *testing.T) {
 	tests := []struct {
 		name     string
-		reviews  []gitea.Review
+		reviews  []vcsReview
 		sentinel string
 		want     bool
 	}{
@@ -314,36 +312,36 @@ func TestHasSharedToken(t *testing.T) {
 		},
 		{
 			name: "no own review yet - cannot detect",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "other"}, Body: "<!-- review-bot:gpt --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "other"}, Body: "<!-- review-bot:gpt --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "separate users - no shared token",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "security-review-bot"}, Body: "<!-- review-bot:security --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "security-review-bot"}, Body: "<!-- review-bot:security --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "shared token detected - same user different sentinels",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:security --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:security --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
 		},
 		{
 			name: "three roles same user",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:security --> body"},
-				{ID: 3, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:gpt --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:security --> body"},
+				{ID: 3, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:gpt --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
@@ -553,7 +551,7 @@ func TestBuildPatternPaths(t *testing.T) {
 func TestEvaluateCIStatus(t *testing.T) {
 	tests := []struct {
 		name       string
-		statuses   []gitea.CommitStatus
+		statuses   []vcsCommitStatus
 		wantPassed bool
 		wantSubstr string
 	}{
@@ -565,7 +563,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "all success",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
@@ -574,7 +572,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "one failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -583,7 +581,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "error status",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "error", Context: "ci/lint", Description: "Lint error"},
 			},
 			wantPassed: false,
@@ -591,7 +589,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "pending treated as not-failed",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "pending", Context: "ci/build", Description: "In progress"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
@@ -600,7 +598,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "multiple failures",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "failure", Context: "ci/build", Description: "Build failed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -609,7 +607,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "mixed with pending and failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "pending", Context: "ci/deploy", Description: "Deploying"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
@@ -632,6 +630,48 @@ func TestEvaluateCIStatus(t *testing.T) {
 	}
 }

+func TestGithubAPIURL(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{
+			name:  "empty string defaults to api.github.com",
+			input: "",
+			want:  "https://api.github.com",
+		},
+		{
+			name:  "github.com maps to api.github.com",
+			input: "https://github.com",
+			want:  "https://api.github.com",
+		},
+		{
+			name:  "github.com with trailing slash maps to api.github.com",
+			input: "https://github.com/",
+			want:  "https://api.github.com",
+		},
+		{
+			name:  "GHES host gets /api/v3 suffix",
+			input: "https://ghe.example.com",
+			want:  "https://ghe.example.com/api/v3",
+		},
+		{
+			name:  "GHES concur domain does not map to api.github.com",
+			input: "https://github.concur.com",
+			want:  "https://github.concur.com/api/v3",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := githubAPIURL(tt.input)
+			if got != tt.want {
+				t.Errorf("githubAPIURL(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
 func TestEnvOrDefault(t *testing.T) {
 	// Test with unset env var
 	os.Unsetenv("TEST_ENV_OR_DEFAULT_UNSET")
@@ -972,7 +1012,7 @@ func TestMainSubprocess_InvalidProvider(t *testing.T) {
 	}
 }

-// cleanEnv returns environ without any GITEA/LLM/REVIEWER env vars that would
+// cleanEnv returns environ without any GITEA/LLM/REVIEWER/VCS env vars that would
 // interfere with testing missing-flag scenarios.
 func cleanEnv() []string {
 	var env []string
@@ -987,7 +1027,8 @@ func cleanEnv() []string {
 			strings.HasPrefix(key, "CONVENTIONS_"),
 			strings.HasPrefix(key, "SYSTEM_PROMPT_"),
 			strings.HasPrefix(key, "PATTERNS_"),
-			strings.HasPrefix(key, "UPDATE_"):
+			strings.HasPrefix(key, "UPDATE_"),
+			strings.HasPrefix(key, "VCS_"):
 			continue
 		default:
 			env = append(env, e)
@@ -997,7 +1038,7 @@ func cleanEnv() []string {
 }

 func TestFindAllOwnReviews(t *testing.T) {
-	reviews := []gitea.Review{
+	reviews := []vcsReview{
 		{ID: 1, Body: "<!-- review-bot:sonnet -->\nfirst review"},
 		{ID: 2, Body: "<!-- review-bot:gpt -->\nother bot"},
 		{ID: 3, Body: "<!-- review-bot:sonnet -->\nsecond review"},
@@ -0,0 +1,125 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"strings"
+	"time"
+
+	"gitea.weiker.me/rodin/review-bot/gitea"
+)
+
+// runValidateURL implements the `review-bot validate-url <url>` subcommand.
+//
+// It resolves the given URL's hostname and checks that every returned IP is
+// publicly routable (not RFC1918, loopback, link-local, or other reserved
+// ranges). The exit code communicates the result to callers:
+//
+//	0 — URL is safe to use
+//	1 — URL resolves to a blocked/private address
+//	2 — URL is malformed, has an unsafe scheme, or DNS lookup failed
+//
+// This is intended for use from action.yml shell steps that need to validate
+// a user-supplied URL before passing it to curl.
+func runValidateURL(args []string) int {
+	if len(args) != 1 {
+		fmt.Fprintln(errWriter, "usage: review-bot validate-url <url>")
+		fmt.Fprintln(errWriter, "")
+		fmt.Fprintln(errWriter, "Resolves <url> and verifies all resolved IPs are publicly routable.")
+		fmt.Fprintln(errWriter, "Exit 0=safe, 1=blocked, 2=error")
+		return 2
+	}
+	rawURL := args[0]
+
+	if err := validateURL(rawURL); err != nil {
+		fmt.Fprintf(errWriter, "Error: %v\n", err)
+		var ve *validateError
+		if isValidateError(err, &ve) {
+			return ve.code
+		}
+		return 2
+	}
+	fmt.Fprintf(outWriter, "OK: %s is safe\n", rawURL)
+	return 0
+}
+
+// validateError carries an exit code alongside a message.
+type validateError struct {
+	code    int
+	message string
+}
+
+func (e *validateError) Error() string { return e.message }
+
+// isValidateError checks if err is or wraps a *validateError and sets out.
+// Uses errors.As so that wrapped *validateError values (e.g. from fmt.Errorf("...: %w", &validateError{...}))
+// are also detected, making the function robust against future wrapping.
+func isValidateError(err error, out **validateError) bool {
+	if err == nil {
+		return false
+	}
+	return errors.As(err, out)
+}
+
+// validateURL checks that rawURL is safe for use as a Gitea server URL:
+//   - Must be https:// (not http://)
+//   - Must have no user-info (user:pass@host)
+//   - Must resolve to at least one IP, all of which are publicly routable
+func validateURL(rawURL string) error {
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		return &validateError{code: 2, message: fmt.Sprintf("malformed URL %q: %v", rawURL, err)}
+	}
+
+	// Scheme check: only https is permitted.
+	if !strings.EqualFold(parsed.Scheme, "https") {
+		return &validateError{
+			code:    2,
+			message: fmt.Sprintf("URL scheme must be https (got %q)", parsed.Scheme),
+		}
+	}
+
+	// Reject user-info (user:password@host) to prevent credential embedding.
+	if parsed.User != nil {
+		return &validateError{
+			code:    2,
+			message: "URL must not contain user-info (user:password@host)",
+		}
+	}
+
+	host := parsed.Hostname()
+	if host == "" {
+		return &validateError{code: 2, message: fmt.Sprintf("URL has no host: %q", rawURL)}
+	}
+
+	// Resolve the hostname with a short timeout.
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	addrs, err := net.DefaultResolver.LookupIPAddr(ctx, host)
+	if err != nil {
+		return &validateError{
+			code:    2,
+			message: fmt.Sprintf("DNS lookup failed for %q: %v", host, err),
+		}
+	}
+	if len(addrs) == 0 {
+		return &validateError{
+			code:    2,
+			message: fmt.Sprintf("DNS lookup returned no addresses for %q", host),
+		}
+	}
+
+	for _, a := range addrs {
+		if gitea.IsBlockedIP(a.IP) {
+			return &validateError{
+				code:    1,
+				message: fmt.Sprintf("blocked: %q resolves to private/reserved IP %s", host, a.IP),
+			}
+		}
+	}
+	return nil
+}
@@ -0,0 +1,127 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestRunValidateURL_Usage(t *testing.T) {
+	var errBuf bytes.Buffer
+	origErr := errWriter
+	errWriter = &errBuf
+	defer func() { errWriter = origErr }()
+
+	code := runValidateURL(nil)
+	if code != 2 {
+		t.Errorf("expected exit code 2 for no args, got %d", code)
+	}
+	if !strings.Contains(errBuf.String(), "usage") {
+		t.Errorf("expected usage in stderr, got %q", errBuf.String())
+	}
+
+	errBuf.Reset()
+	code = runValidateURL([]string{"arg1", "arg2"})
+	if code != 2 {
+		t.Errorf("expected exit code 2 for too many args, got %d", code)
+	}
+}
+
+func TestValidateURL_MalformedURL(t *testing.T) {
+	cases := []struct {
+		name    string
+		url     string
+		wantMsg string
+	}{
+		{"empty", "", "must be https"},
+		{"http scheme", "http://example.com/", "must be https"},
+		{"ftp scheme", "ftp://example.com/", "must be https"},
+		{"no scheme", "example.com", "must be https"},
+		{"user info", "https://user:pass@example.com/", "user-info"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := validateURL(tc.url)
+			if err == nil {
+				t.Errorf("expected error for URL %q, got nil", tc.url)
+				return
+			}
+			if !strings.Contains(err.Error(), tc.wantMsg) {
+				t.Errorf("error %q does not contain %q", err.Error(), tc.wantMsg)
+			}
+			var ve *validateError
+			if !isValidateError(err, &ve) {
+				t.Fatalf("expected *validateError, got %T", err)
+			}
+			if ve.code != 2 {
+				t.Errorf("expected code 2, got %d", ve.code)
+			}
+		})
+	}
+}
+
+func TestValidateURL_BlockedPrivateIP(t *testing.T) {
+	// localhost always resolves to 127.0.0.1 (loopback).
+	err := validateURL("https://localhost/")
+	if err == nil {
+		t.Skip("localhost did not resolve (network unavailable in test environment)")
+	}
+	var ve *validateError
+	if !isValidateError(err, &ve) {
+		t.Fatalf("expected *validateError, got %T: %v", err, err)
+	}
+	if ve.code != 1 && ve.code != 2 {
+		t.Errorf("expected code 1 (blocked) or 2 (dns fail), got %d: %s", ve.code, ve.message)
+	}
+	// If it resolved (code 1), the message must say "blocked".
+	if ve.code == 1 && !strings.Contains(ve.message, "blocked") {
+		t.Errorf("expected 'blocked' in message, got %q", ve.message)
+	}
+}
+
+func TestValidateURL_ExitCodes(t *testing.T) {
+	cases := []struct {
+		name     string
+		url      string
+		wantCode int
+	}{
+		{"http scheme", "http://example.com/", 2},
+		{"no scheme", "example.com", 2},
+		{"user info", "https://admin:secret@example.com/", 2},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := validateURL(tc.url)
+			if err == nil {
+				t.Fatalf("expected error for %q", tc.url)
+			}
+			var ve *validateError
+			if !isValidateError(err, &ve) {
+				t.Fatalf("expected *validateError, got %T", err)
+			}
+			if ve.code != tc.wantCode {
+				t.Errorf("code = %d, want %d (url=%q, msg=%s)", ve.code, tc.wantCode, tc.url, ve.message)
+			}
+		})
+	}
+}
+
+func TestRunValidateURL_WithCapture(t *testing.T) {
+	var outBuf, errBuf bytes.Buffer
+	origOut, origErr := outWriter, errWriter
+	outWriter = &outBuf
+	errWriter = &errBuf
+	defer func() {
+		outWriter = origOut
+		errWriter = origErr
+	}()
+
+	// http:// scheme should fail with code 2.
+	code := runValidateURL([]string{"http://example.com/"})
+	if code != 2 {
+		t.Errorf("expected code 2 for http:// URL, got %d", code)
+	}
+	if !strings.Contains(errBuf.String(), "must be https") {
+		t.Errorf("expected error about https in stderr, got %q", errBuf.String())
+	}
+}
@@ -0,0 +1,361 @@
+package main
+
+// vcs.go defines the vcsClient interface that both gitea.Client (via giteaVCSAdapter)
+// and github.Client (via githubVCSAdapter) satisfy, enabling VCS-type routing in main.go.
+//
+// Interface design:
+//   - Methods cover all PR review operations used by main.go.
+//   - Gitea-specific operations (supersede, comment resolution) are in the separate
+//     giteaExtClient interface. GitHub implementations return ErrNotSupported for those.
+//   - Types are defined here as package-local VCS types; each adapter converts from
+//     its respective client package's types.
+
+import (
+	"context"
+	"errors"
+
+	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/github"
+	"gitea.weiker.me/rodin/review-bot/review"
+)
+
+// ErrNotSupported is returned by VCS methods that have no implementation for
+// a particular VCS backend (e.g., Gitea-specific timeline APIs on GitHub).
+var ErrNotSupported = errors.New("operation not supported on this VCS backend")
+
+// vcsClient is the interface for all PR operations used by main.go.
+// It is implemented by both giteaVCSAdapter and githubVCSAdapter.
+// Interface defined here (in the consumer package) per Go idiom.
+type vcsClient interface {
+	// PR metadata and content
+	GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error)
+	GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
+	GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error)
+	GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error)
+	GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error)
+	GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error)
+	ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error)
+	GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error)
+
+	// Review operations
+	PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error)
+	ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error)
+	DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
+	GetAuthenticatedUser(ctx context.Context) (string, error)
+	RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error
+}
+
+// giteaExtClient extends vcsClient with Gitea-specific operations that have no
+// GitHub equivalent. Code that uses these methods should first do a type assertion.
+type giteaExtClient interface {
+	vcsClient
+	GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error)
+	EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error
+	ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error)
+	ResolveComment(ctx context.Context, owner, repo string, commentID int64) error
+}
+
+// --- shared VCS types ---
+
+// vcsPullRequest is VCS-agnostic PR metadata.
+type vcsPullRequest struct {
+	Title string
+	Body  string
+	Head  struct {
+		Sha string
+		Ref string
+	}
+}
+
+// vcsChangedFile is a file changed in a PR.
+type vcsChangedFile struct {
+	Filename string
+	Status   string
+}
+
+// vcsCommitStatus is a CI status entry.
+type vcsCommitStatus struct {
+	Status      string
+	Context     string
+	Description string
+	TargetURL   string
+}
+
+// vcsReviewComment is an inline review comment.
+type vcsReviewComment struct {
+	Path        string
+	NewPosition int64 // Gitea: absolute line; GitHub: diff hunk position
+	Body        string
+}
+
+// vcsReview is a submitted PR review.
+type vcsReview struct {
+	ID       int64
+	Body     string
+	CommitID string
+	User     struct {
+		Login string
+	}
+	State string
+}
+
+// ============================================================
+// giteaVCSAdapter
+// ============================================================
+
+// giteaVCSAdapter wraps gitea.Client to implement vcsClient + giteaExtClient.
+type giteaVCSAdapter struct {
+	c *gitea.Client
+}
+
+func newGiteaVCSAdapter(c *gitea.Client) *giteaVCSAdapter { return &giteaVCSAdapter{c: c} }
+
+func (a *giteaVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
+	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
+	r.Head.Sha = pr.Head.Sha
+	r.Head.Ref = pr.Head.Ref
+	return r, nil
+}
+
+func (a *giteaVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
+}
+
+func (a *giteaVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
+	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsChangedFile, len(files))
+	for i, f := range files {
+		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
+	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsCommitStatus, len(statuses))
+	for i, s := range statuses {
+		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return a.c.GetFileContent(ctx, owner, repo, filepath)
+}
+
+func (a *giteaVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
+}
+
+func (a *giteaVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
+	entries, err := a.c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]review.ContentEntry, len(entries))
+	for i, e := range entries {
+		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
+}
+
+func (a *giteaVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
+	gc := make([]gitea.ReviewComment, len(comments))
+	for i, c := range comments {
+		gc[i] = gitea.ReviewComment{Path: c.Path, NewPosition: c.NewPosition, Body: c.Body}
+	}
+	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
+	if err != nil {
+		return nil, err
+	}
+	out := &vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
+	out.User.Login = r.User.Login
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
+	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsReview, len(reviews))
+	for i, r := range reviews {
+		out[i] = vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
+		out[i].User.Login = r.User.Login
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
+}
+
+func (a *giteaVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	return a.c.GetAuthenticatedUser(ctx)
+}
+
+func (a *giteaVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
+}
+
+// Gitea-specific extension methods.
+
+func (a *giteaVCSAdapter) GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error) {
+	return a.c.GetTimelineReviewCommentIDForReview(ctx, owner, repo, int(prNum), reviewID)
+}
+
+func (a *giteaVCSAdapter) EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error {
+	return a.c.EditComment(ctx, owner, repo, commentID, body)
+}
+
+func (a *giteaVCSAdapter) ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error) {
+	return a.c.ListReviewComments(ctx, owner, repo, int(prNum), reviewID)
+}
+
+func (a *giteaVCSAdapter) ResolveComment(ctx context.Context, owner, repo string, commentID int64) error {
+	return a.c.ResolveComment(ctx, owner, repo, commentID)
+}
+
+// ============================================================
+// githubVCSAdapter
+// ============================================================
+
+// githubVCSAdapter wraps github.Client to implement vcsClient.
+// Gitea-specific extension methods (GetTimelineReviewCommentIDForReview, EditComment,
+// ListReviewComments, ResolveComment) are not available on GitHub and will not be called
+// because main.go gates them with a type assertion to giteaExtClient.
+type githubVCSAdapter struct {
+	c *github.Client
+}
+
+func newGithubVCSAdapter(c *github.Client) *githubVCSAdapter { return &githubVCSAdapter{c: c} }
+
+func (a *githubVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
+	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
+	r.Head.Sha = pr.Head.Sha
+	r.Head.Ref = pr.Head.Ref
+	return r, nil
+}
+
+func (a *githubVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
+}
+
+func (a *githubVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
+	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsChangedFile, len(files))
+	for i, f := range files {
+		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
+	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsCommitStatus, len(statuses))
+	for i, s := range statuses {
+		// CommitStatus.Status is tagged as json:"state" — already the normalized "state" value
+		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return a.c.GetFileContent(ctx, owner, repo, filepath)
+}
+
+func (a *githubVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
+}
+
+func (a *githubVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
+	entries, err := a.c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]review.ContentEntry, len(entries))
+	for i, e := range entries {
+		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
+}
+
+func (a *githubVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
+	gc := make([]github.ReviewComment, len(comments))
+	for i, c := range comments {
+		// GitHub inline comments use diff hunk "position", not absolute line numbers.
+		// NewPosition from gitea diff parsing gives absolute line numbers, which
+		// will not match GitHub's position values. For initial GitHub support, we
+		// attach comments with Line+Side (absolute line on the RIGHT side) instead.
+		// Comments that cannot be mapped will be omitted (GitHub rejects invalid positions).
+		gc[i] = github.ReviewComment{
+			Path: c.Path,
+			Line: c.NewPosition,
+			Side: "RIGHT",
+			Body: c.Body,
+		}
+	}
+	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
+	if err != nil {
+		return nil, err
+	}
+	out := &vcsReview{ID: r.ID, Body: r.Body, State: r.State}
+	out.User.Login = r.User.Login
+	return out, nil
+}
+
+func (a *githubVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
+	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsReview, len(reviews))
+	for i, r := range reviews {
+		out[i] = vcsReview{ID: r.ID, Body: r.Body, State: r.State}
+		out[i].User.Login = r.User.Login
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	// GitHub only allows deleting PENDING (draft) reviews. review-bot posts submitted
+	// reviews, so this will return an error for any review we actually posted.
+	// Callers should treat 422 errors here gracefully.
+	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
+}
+
+func (a *githubVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	return a.c.GetAuthenticatedUser(ctx)
+}
+
+func (a *githubVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
+}
@@ -78,18 +78,142 @@ type Client struct {
 	MaxDiffSize int64
 }

+// defaultCheckRedirect is the redirect policy used by NewClient.
+// NOTE: This function is intentionally duplicated in github/client.go (and vice versa)
+// because the packages are separate. Changes here must be mirrored there.
+// It rejects HTTPS->HTTP protocol downgrades (to prevent plaintext leakage)
+// and cross-host redirects (to prevent following responses from untrusted
+// endpoints). Same-host, same-or-upgraded-scheme redirects are allowed.
+func defaultCheckRedirect(req *http.Request, via []*http.Request) error {
+	if len(via) >= 10 {
+		return fmt.Errorf("stopped after 10 redirects")
+	}
+	// Guard for direct invocation in tests and any future callers;
+	// net/http guarantees len(via) >= 1 during actual redirects.
+	if len(via) == 0 {
+		return nil
+	}
+	prev := via[len(via)-1]
+	// Reject protocol downgrade: HTTPS->HTTP leaks request metadata over plaintext.
+	if prev.URL.Scheme == "https" && req.URL.Scheme == "http" {
+		return fmt.Errorf("refusing redirect: HTTPS to HTTP downgrade (%s -> %s)", prev.URL.Host, req.URL.Host)
+	}
+	// Reject cross-host redirect entirely to avoid consuming responses
+	// from untrusted endpoints.
+	if req.URL.Host != prev.URL.Host {
+		return fmt.Errorf("refusing redirect: cross-host (%s -> %s)", prev.URL.Host, req.URL.Host)
+	}
+	return nil
+}
+
+// safeDialContext is the default DialContext for NewClient.
+// It resolves the hostname and checks every returned IP against the blocked
+// CIDR list before establishing a connection. This prevents SSRF attacks
+// where user-supplied URLs resolve to internal/private addresses.
+//
+// After validating all IPs, we dial the first resolved IP directly to avoid
+// a second DNS lookup (which could return a different IP in a DNS rebinding
+// attack). This narrows — but does not fully eliminate — the DNS rebinding
+// window to the time between LookupIPAddr and DialContext.
+//
+// If the host is already an IP literal, LookupIPAddr returns it directly
+// (no DNS query issued), so IP literals like https://127.0.0.1/ are blocked.
+func safeDialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, fmt.Errorf("safeDialContext: invalid address %q: %w", addr, err)
+	}
+	addrs, err := net.DefaultResolver.LookupIPAddr(ctx, host)
+	if err != nil {
+		return nil, fmt.Errorf("safeDialContext: DNS lookup %q: %w", host, err)
+	}
+	if len(addrs) == 0 {
+		return nil, fmt.Errorf("safeDialContext: no addresses returned for %q", host)
+	}
+	for _, a := range addrs {
+		if IsBlockedIP(a.IP) {
+			return nil, fmt.Errorf("safeDialContext: blocked: %q resolves to private/reserved IP %s", host, a.IP)
+		}
+	}
+	// Try each resolved IP in order, returning the first successful connection.
+	// Fallback is important when a hostname resolves to multiple IPs and the first
+	// is temporarily unreachable. All IPs were already validated above, so dialing
+	// any of them is safe.
+	//
+	// Timeout: 10s per the design (PLAN.md); the outer http.Client has a 30s
+	// total timeout, but the per-dial timeout ensures a slow TCP connect on one IP
+	// doesn't consume the budget needed to try others.
+	d := &net.Dialer{Timeout: 10 * time.Second}
+	var lastErr error
+	for _, a := range addrs {
+		conn, err := d.DialContext(ctx, network, net.JoinHostPort(a.IP.String(), port))
+		if err == nil {
+			return conn, nil
+		}
+		lastErr = err
+	}
+	return nil, fmt.Errorf("safeDialContext: all %d addresses for %q failed, last error: %w", len(addrs), host, lastErr)
+}
+
+// newSafeHTTPClient returns an *http.Client with the SSRF-blocking safeDialContext
+// transport and the cross-host redirect rejection policy.
+//
+// We clone http.DefaultTransport to preserve its production-ready defaults
+// (ProxyFromEnvironment, TLSHandshakeTimeout, IdleConnTimeout, connection
+// pooling, HTTP/2 support) and override only DialContext with safeDialContext.
+func newSafeHTTPClient() *http.Client {
+	transport := http.DefaultTransport.(*http.Transport).Clone()
+	transport.DialContext = safeDialContext
+	return &http.Client{
+		Timeout:       30 * time.Second,
+		Transport:     transport,
+		CheckRedirect: defaultCheckRedirect,
+	}
+}
+
 // NewClient creates a new Gitea API client.
+//
+// The client uses a safe HTTP transport by default: DNS resolution is performed
+// before connecting and any IP in a private/reserved range is rejected
+// (RFC1918, loopback, link-local, ULA, etc.). Cross-host and HTTPS→HTTP
+// redirects are also rejected.
+//
+// For tests that use httptest.NewServer (which listens on 127.0.0.1), call
+// WithUnsafeDialer() to bypass the IP check.
 func NewClient(baseURL, token string) *Client {
 	return &Client{
 		baseURL: strings.TrimRight(baseURL, "/"),
 		token:   token,
-		http:    &http.Client{Timeout: 30 * time.Second},
+		http:    newSafeHTTPClient(),
 	}
 }

+// WithUnsafeDialer returns the client configured with a plain HTTP client that
+// has no IP-level SSRF protection. It preserves the redirect-rejection policy.
+//
+// This MUST only be used in tests. Production code must never call this method.
+func (c *Client) WithUnsafeDialer() *Client {
+	c.http = &http.Client{
+		Timeout:       30 * time.Second,
+		CheckRedirect: defaultCheckRedirect,
+	}
+	return c
+}
+
 // SetHTTPClient sets the underlying HTTP client used for requests.
-// This is intended for testing to inject mock transports.
+// This is intended for test setup only to inject mock transports; it must be
+// called before any goroutines issue requests.
+//
+// Passing nil restores the default safe client (30s timeout, IP-blocking
+// safeDialContext, and redirect-rejecting CheckRedirect policy matching NewClient).
+//
+// Callers providing a non-nil client are responsible for configuring a safe
+// CheckRedirect policy. Without one, the default net/http behavior will follow
+// redirects and may forward the Authorization header to untrusted hosts.
 func (c *Client) SetHTTPClient(hc *http.Client) {
+	if hc == nil {
+		hc = newSafeHTTPClient()
+	}
 	c.http = hc
 }

@@ -217,18 +341,22 @@ func (c *Client) GetFileContentRef(ctx context.Context, owner, repo, filepath, r
 }

 // PostReview submits a review to a PR and returns the created review.
-// event should be "APPROVED" or "REQUEST_CHANGES".
+// event should be one of "APPROVED", "REQUEST_CHANGES", or "COMMENT".
+// commitID anchors the review to a specific commit SHA. If empty, Gitea
+// defaults to the current PR head.
 // comments are optional inline comments attached to specific lines.
-func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body string, comments []ReviewComment) (*Review, error) {
+func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []ReviewComment) (*Review, error) {
 	reqURL := fmt.Sprintf("%s/api/v1/repos/%s/%s/pulls/%d/reviews", c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)

 	payload := struct {
 		Body     string          `json:"body"`
 		Event    string          `json:"event"`
+		CommitID string          `json:"commit_id,omitempty"`
 		Comments []ReviewComment `json:"comments,omitempty"`
 	}{
 		Body:     body,
 		Event:    event,
+		CommitID: commitID,
 		Comments: comments,
 	}

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"sync/atomic"
 	"syscall"
@@ -35,7 +36,7 @@ func TestGetPullRequest(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	got, err := client.GetPullRequest(context.Background(), "owner", "repo", 1)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -62,7 +63,7 @@ func TestGetPullRequestDiff(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	got, err := client.GetPullRequestDiff(context.Background(), "owner", "repo", 5)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -87,7 +88,7 @@ func TestGetCommitStatuses(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	got, err := client.GetCommitStatuses(context.Background(), "owner", "repo", "abc123")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -116,8 +117,9 @@ func TestPostReview(t *testing.T) {
 		}

 		var payload struct {
-			Body  string `json:"body"`
-			Event string `json:"event"`
+			Body     string `json:"body"`
+			Event    string `json:"event"`
+			CommitID string `json:"commit_id"`
 		}
 		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
 			t.Fatalf("failed to decode payload: %v", err)
@@ -128,14 +130,16 @@ func TestPostReview(t *testing.T) {
 		if payload.Event != "APPROVED" {
 			t.Errorf("expected event %q, got %q", "APPROVED", payload.Event)
 		}
-
+		if payload.CommitID != "abc123def" {
+			t.Errorf("expected commit_id %q, got %q", "abc123def", payload.CommitID)
+		}
 		w.WriteHeader(http.StatusOK)
 		w.Write([]byte(`{"id":100,"user":{"login":"review-bot"},"state":"APPROVED","stale":false}`))
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
-	review, err := client.PostReview(context.Background(), "owner", "repo", 3, "APPROVED", "LGTM", nil)
+	client := NewTestClient(server.URL, "test-token")
+	review, err := client.PostReview(context.Background(), "owner", "repo", 3, "APPROVED", "LGTM", "abc123def", nil)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -154,7 +158,7 @@ func TestGetPullRequest_Non200(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.GetPullRequest(context.Background(), "owner", "repo", 999)
 	if err == nil {
 		t.Fatal("expected error for 404, got nil")
@@ -167,7 +171,7 @@ func TestGetPullRequest_BadJSON(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.GetPullRequest(context.Background(), "owner", "repo", 1)
 	if err == nil {
 		t.Fatal("expected error for bad JSON, got nil")
@@ -181,13 +185,36 @@ func TestPostReview_Non200(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
-	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "APPROVED", "test", nil)
+	client := NewTestClient(server.URL, "test-token")
+	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "APPROVED", "test", "", nil)
 	if err == nil {
 		t.Fatal("expected error for 403, got nil")
 	}
 }

+func TestPostReview_EmptyCommitID_OmittedFromPayload(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		var raw map[string]interface{}
+		if err := json.Unmarshal(body, &raw); err != nil {
+			t.Fatalf("failed to decode payload: %v", err)
+		}
+		if _, exists := raw["commit_id"]; exists {
+			t.Errorf("expected commit_id to be omitted from payload when empty, but it was present")
+		}
+
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"id":200,"user":{"login":"bot"},"state":"APPROVED","stale":false}`))
+	}))
+	defer server.Close()
+
+	client := NewTestClient(server.URL, "test-token")
+	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "APPROVED", "ok", "", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
 func TestGetFileContent(t *testing.T) {
 	expected := "# Conventions\n- Be nice\n"

@@ -199,7 +226,7 @@ func TestGetFileContent(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	got, err := client.GetFileContent(context.Background(), "owner", "repo", "CONVENTIONS.md")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -219,7 +246,7 @@ func TestGetPullRequestFiles(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	files, err := client.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -244,7 +271,7 @@ func TestGetFileContentRef(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	content, err := client.GetFileContentRef(context.Background(), "owner", "repo", "main.go", "feature-branch")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -264,7 +291,7 @@ func TestListContents(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	entries, err := client.ListContents(context.Background(), "owner", "repo", "docs")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -291,7 +318,7 @@ func TestListContents_DotPath(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	entries, err := client.ListContents(context.Background(), "owner", "repo", ".")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -316,7 +343,7 @@ func TestListContents_FilePath(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	entries, err := client.ListContents(context.Background(), "owner", "repo", "README.md")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -348,7 +375,7 @@ func TestGetAllFilesInPath_File(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	files, err := client.GetAllFilesInPath(context.Background(), "owner", "repo", "README.md")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -401,7 +428,7 @@ func TestListReviews(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	reviews, err := client.ListReviews(context.Background(), "owner", "repo", 5)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -441,7 +468,7 @@ func TestListReviews_Pagination(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	reviews, err := client.ListReviews(context.Background(), "owner", "repo", 5)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -466,7 +493,7 @@ func TestDeleteReview(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.DeleteReview(context.Background(), "owner", "repo", 5, 10)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -480,7 +507,7 @@ func TestDeleteReview_Forbidden(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.DeleteReview(context.Background(), "owner", "repo", 5, 10)
 	if err == nil {
 		t.Fatal("expected error for 403, got nil")
@@ -509,7 +536,7 @@ func TestEditComment(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.EditComment(context.Background(), "owner", "repo", 42, "updated body")
 	if err != nil {
 		t.Fatalf("EditComment() error = %v", err)
@@ -523,7 +550,7 @@ func TestEditComment_Forbidden(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.EditComment(context.Background(), "owner", "repo", 42, "new body")
 	if err == nil {
 		t.Fatal("expected error for 403 response")
@@ -543,7 +570,7 @@ func TestGetTimelineReviewCommentID(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	id, err := client.GetTimelineReviewCommentID(context.Background(), "owner", "repo", 5, "<!-- review-bot:sonnet -->")
 	if err != nil {
 		t.Fatalf("GetTimelineReviewCommentID() error = %v", err)
@@ -559,7 +586,7 @@ func TestGetTimelineReviewCommentID_NotFound(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.GetTimelineReviewCommentID(context.Background(), "owner", "repo", 5, "<!-- review-bot:sonnet -->")
 	if err == nil {
 		t.Fatal("expected error when sentinel not found")
@@ -582,7 +609,7 @@ func TestGetAllFilesInPath_404FallsBackToFile(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	files, err := client.GetAllFilesInPath(context.Background(), "owner", "repo", "README.md")
 	if err != nil {
 		t.Fatalf("expected fallback to file on 404, got error: %v", err)
@@ -603,7 +630,7 @@ func TestGetAllFilesInPath_500Propagates(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.GetAllFilesInPath(context.Background(), "owner", "repo", "somepath")
 	if err == nil {
 		t.Fatal("expected error to propagate for 500, got nil")
@@ -625,7 +652,7 @@ func TestGetAllFilesInPath_403Propagates(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.GetAllFilesInPath(context.Background(), "owner", "repo", "private/stuff")
 	if err == nil {
 		t.Fatal("expected error to propagate for 403, got nil")
@@ -677,7 +704,7 @@ func TestGetAuthenticatedUser(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	login, err := client.GetAuthenticatedUser(context.Background())
 	if err != nil {
 		t.Fatalf("GetAuthenticatedUser() error = %v", err)
@@ -702,7 +729,7 @@ func TestRequestReviewer(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.RequestReviewer(context.Background(), "owner", "repo", 7, "bot-user")
 	if err != nil {
 		t.Fatalf("RequestReviewer() error = %v", err)
@@ -718,7 +745,7 @@ func TestRequestReviewer_204(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.RequestReviewer(context.Background(), "owner", "repo", 1, "user")
 	if err != nil {
 		t.Fatalf("RequestReviewer() should accept 204, got error = %v", err)
@@ -732,7 +759,7 @@ func TestRequestReviewer_Error(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.RequestReviewer(context.Background(), "owner", "repo", 1, "user")
 	if err == nil {
 		t.Fatal("expected error for 403 response")
@@ -752,7 +779,7 @@ func TestListReviewComments(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	comments, err := client.ListReviewComments(context.Background(), "owner", "repo", 1, 42)
 	if err != nil {
 		t.Fatalf("ListReviewComments() error = %v", err)
@@ -780,7 +807,7 @@ func TestResolveComment(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.ResolveComment(context.Background(), "owner", "repo", 99)
 	if err != nil {
 		t.Fatalf("ResolveComment() error = %v", err)
@@ -794,7 +821,7 @@ func TestResolveComment_Error(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	err := client.ResolveComment(context.Background(), "owner", "repo", 99)
 	if err == nil {
 		t.Fatal("expected error for 404 response")
@@ -843,7 +870,7 @@ func TestDoGet_RetriesOn500(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	// Use short backoff for fast tests
 	client.RetryBackoff = []time.Duration{1 * time.Millisecond, 1 * time.Millisecond}

@@ -868,7 +895,7 @@ func TestDoGet_FailsAfterMaxRetries(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	// Use short backoff for fast tests
 	client.RetryBackoff = []time.Duration{1 * time.Millisecond, 1 * time.Millisecond}

@@ -897,7 +924,7 @@ func TestDoGet_NoRetryOn4xx(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	_, err := client.doGet(context.Background(), server.URL+"/test")
 	if err == nil {
 		t.Fatal("expected error for 403")
@@ -925,7 +952,7 @@ func TestDoGet_RespectsContextCancellation(t *testing.T) {

 	ctx, cancel := context.WithCancel(context.Background())

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	// Use longer backoff to give us time to cancel during the wait
 	client.RetryBackoff = []time.Duration{100 * time.Millisecond, 100 * time.Millisecond}

@@ -944,8 +971,6 @@ func TestDoGet_RespectsContextCancellation(t *testing.T) {
 		t.Errorf("attempts = %d, expected 1 before context cancel during backoff", attempts)
 	}
 }
-
-
 // mockTransport is a test helper that returns errors for the first N calls,
 // then delegates to a real server.
 type mockTransport struct {
@@ -1159,3 +1184,238 @@ func TestSanitizeErrorForLog(t *testing.T) {
 		})
 	}
 }
+
+func TestNewClient_HasCheckRedirect(t *testing.T) {
+	c := NewClient("https://gitea.example.com", "token")
+	if c.http.CheckRedirect == nil {
+		t.Fatal("expected CheckRedirect to be set")
+	}
+}
+
+func TestDefaultCheckRedirect_RejectsHTTPSToHTTP(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "http", Host: "gitea.example.com", Path: "/foo"},
+		Header: http.Header{"Authorization": []string{"token abc"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err == nil {
+		t.Fatal("expected error on HTTPS->HTTP redirect")
+	}
+	if !strings.Contains(err.Error(), "HTTPS to HTTP downgrade") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDefaultCheckRedirect_RejectsCrossHost(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "https", Host: "cdn.example.com", Path: "/bar"},
+		Header: http.Header{"Authorization": []string{"token abc"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err == nil {
+		t.Fatal("expected error on cross-host redirect")
+	}
+	if !strings.Contains(err.Error(), "cross-host") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDefaultCheckRedirect_AllowsSameHost(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/bar"},
+		Header: http.Header{"Authorization": []string{"token abc"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if auth := req.Header.Get("Authorization"); auth != "token abc" {
+		t.Errorf("expected Authorization to be preserved, got %q", auth)
+	}
+}
+
+func TestDefaultCheckRedirect_AllowsSameHostHTTPToHTTP(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "http", Host: "localhost:3000", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "http", Host: "localhost:3000", Path: "/bar"},
+		Header: http.Header{},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestDefaultCheckRedirect_RejectsTooManyRedirects(t *testing.T) {
+	via := make([]*http.Request, 10)
+	for i := range via {
+		via[i] = &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/"}}
+	}
+	req := &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/final"}}
+	err := defaultCheckRedirect(req, via)
+	if err == nil {
+		t.Fatal("expected error after 10 redirects")
+	}
+	if !strings.Contains(err.Error(), "10 redirects") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDefaultCheckRedirect_EmptyViaAllowed(t *testing.T) {
+	req := &http.Request{URL: &url.URL{Scheme: "https", Host: "gitea.example.com", Path: "/foo"}}
+	err := defaultCheckRedirect(req, nil)
+	if err != nil {
+		t.Fatalf("unexpected error with empty via: %v", err)
+	}
+}
+
+func TestSetHTTPClient_NilRestoresDefault(t *testing.T) {
+	c := NewClient("https://gitea.example.com", "token")
+	c.SetHTTPClient(nil)
+	if c.http == nil {
+		t.Fatal("expected non-nil http client after SetHTTPClient(nil)")
+	}
+	if c.http.Timeout != 30*time.Second {
+		t.Errorf("expected 30s timeout, got %v", c.http.Timeout)
+	}
+	if c.http.CheckRedirect == nil {
+		t.Fatal("expected CheckRedirect policy after SetHTTPClient(nil)")
+	}
+}
+
+// TestSafeDialContextBlocksPrivateIPs verifies that NewClient (which uses
+// safeDialContext by default) refuses to connect to private/reserved IPs.
+func TestSafeDialContextBlocksPrivateIPs(t *testing.T) {
+	// These servers listen on 127.0.0.1, so the safe dialer will block them.
+	// We use NewClient (NOT NewTestClient) to exercise the real safe dialer.
+	privateURLs := []struct {
+		name string
+		url  string
+	}{
+		{"loopback localhost", "http://localhost/"},
+		{"loopback 127.0.0.1", "http://127.0.0.1/"},
+	}
+
+	for _, tc := range privateURLs {
+		t.Run(tc.name, func(t *testing.T) {
+			c := NewClient(tc.url, "token")
+			_, err := c.GetPullRequest(context.Background(), "owner", "repo", 1)
+			if err == nil {
+				t.Errorf("expected error connecting to %s, got nil", tc.url)
+			}
+			// Error must mention SSRF/blocked, not a random network error.
+			if !strings.Contains(err.Error(), "blocked") &&
+				!strings.Contains(err.Error(), "private") &&
+				!strings.Contains(err.Error(), "loopback") &&
+				!strings.Contains(err.Error(), "reserved") {
+				t.Logf("error: %v", err)
+				// Allow other errors (connection refused, DNS) since the point
+				// is that we don't silently succeed — but prefer the explicit block message.
+			}
+		})
+	}
+}
+
+// TestWithUnsafeDialerAllowsLocalhost verifies that WithUnsafeDialer bypasses
+// the IP check, allowing tests to connect to httptest.Server (127.0.0.1).
+func TestWithUnsafeDialerAllowsLocalhost(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`{"title":"test","body":"","head":{"sha":"abc","ref":"main"}}`))
+	}))
+	defer server.Close()
+
+	// WithUnsafeDialer should allow connecting to 127.0.0.1.
+	c := NewClient(server.URL, "token").WithUnsafeDialer()
+	pr, err := c.GetPullRequest(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error with unsafe dialer: %v", err)
+	}
+	if pr.Title != "test" {
+		t.Errorf("expected title 'test', got %q", pr.Title)
+	}
+}
+
+// TestNewClient_HasSafeTransport verifies that NewClient installs the
+// SSRF-blocking transport (i.e. Transport is not nil and DialContext is set).
+func TestNewClient_HasSafeTransport(t *testing.T) {
+	c := NewClient("https://gitea.example.com", "token")
+	if c.http.Transport == nil {
+		t.Fatal("expected Transport to be set on NewClient (safe dialer)")
+	}
+	transport, ok := c.http.Transport.(*http.Transport)
+	if !ok {
+		t.Fatalf("expected *http.Transport, got %T", c.http.Transport)
+	}
+	if transport.DialContext == nil {
+		t.Fatal("expected DialContext to be set on transport (safe dialer)")
+	}
+}
+
+// TestSetHTTPClient_NilRestoresSafeTransport verifies that SetHTTPClient(nil)
+// restores the safe transport (not just any client).
+func TestSetHTTPClient_NilRestoresSafeTransport(t *testing.T) {
+	c := NewClient("https://gitea.example.com", "token")
+	c.SetHTTPClient(&http.Client{}) // replace with plain client
+	c.SetHTTPClient(nil)            // restore
+	transport, ok := c.http.Transport.(*http.Transport)
+	if !ok {
+		t.Fatalf("expected *http.Transport after SetHTTPClient(nil), got %T", c.http.Transport)
+	}
+	if transport.DialContext == nil {
+		t.Fatal("expected DialContext to be restored after SetHTTPClient(nil)")
+	}
+}
+
+// TestNewSafeHTTPClient_PreservesDefaultTransportSettings verifies that
+// newSafeHTTPClient clones http.DefaultTransport to retain proxy support,
+// TLS handshake timeout, idle connection limits, and HTTP/2.
+func TestNewSafeHTTPClient_PreservesDefaultTransportSettings(t *testing.T) {
+	c := NewClient("https://gitea.example.com", "token")
+	transport, ok := c.http.Transport.(*http.Transport)
+	if !ok {
+		t.Fatalf("expected *http.Transport, got %T", c.http.Transport)
+	}
+
+	defaults := http.DefaultTransport.(*http.Transport)
+
+	// TLSHandshakeTimeout must be inherited (non-zero), not the zero value
+	// that a bare &http.Transport{} would have.
+	if transport.TLSHandshakeTimeout == 0 {
+		t.Error("TLSHandshakeTimeout is 0; expected inherited value from DefaultTransport")
+	}
+	if transport.TLSHandshakeTimeout != defaults.TLSHandshakeTimeout {
+		t.Errorf("TLSHandshakeTimeout = %v, want %v", transport.TLSHandshakeTimeout, defaults.TLSHandshakeTimeout)
+	}
+
+	// IdleConnTimeout must be inherited.
+	if transport.IdleConnTimeout == 0 {
+		t.Error("IdleConnTimeout is 0; expected inherited value from DefaultTransport")
+	}
+	if transport.IdleConnTimeout != defaults.IdleConnTimeout {
+		t.Errorf("IdleConnTimeout = %v, want %v", transport.IdleConnTimeout, defaults.IdleConnTimeout)
+	}
+
+	// MaxIdleConns must be inherited.
+	if transport.MaxIdleConns == 0 {
+		t.Error("MaxIdleConns is 0; expected inherited value from DefaultTransport")
+	}
+
+	// ForceAttemptHTTP2 must be inherited.
+	if !transport.ForceAttemptHTTP2 {
+		t.Error("ForceAttemptHTTP2 is false; expected true from DefaultTransport")
+	}
+
+	// Proxy must be set (ProxyFromEnvironment).
+	if transport.Proxy == nil {
+		t.Error("Proxy is nil; expected ProxyFromEnvironment from DefaultTransport")
+	}
+
+	// DialContext must be our safe dialer, not the default.
+	if transport.DialContext == nil {
+		t.Error("DialContext is nil; expected safeDialContext")
+	}
+}
@@ -70,7 +70,7 @@ func TestGetPullRequestDiff_SizeLimits(t *testing.T) {
 			}))
 			defer server.Close()

-			client := NewClient(server.URL, "test-token")
+			client := NewTestClient(server.URL, "test-token")
 			client.MaxDiffSize = tt.maxDiffSize
 			client.RetryBackoff = []time.Duration{}

@@ -0,0 +1,18 @@
+// Package gitea — export_test.go exposes test helpers to test files in this
+// package. It uses `package gitea` (not `package gitea_test`) so it can access
+// unexported identifiers; Go only compiles it into the test binary, never into
+// the production binary. This is the idiomatic pattern for white-box testing
+// in Go (see net/http/export_test.go in the stdlib for the same approach).
+package gitea
+
+// NewTestClient creates a Gitea client configured for use in unit tests.
+// It bypasses the IP-level SSRF protection so that tests can connect to
+// httptest.Server instances (which listen on 127.0.0.1).
+//
+// Using the internal package gitea declaration (not gitea_test) means this
+// symbol is available to all _test.go files in this package. It is ONLY
+// compiled into the test binary; production binaries never include it.
+// Production code must use NewClient, which enables the safe dialer.
+func NewTestClient(baseURL, token string) *Client {
+	return NewClient(baseURL, token).WithUnsafeDialer()
+}
@@ -0,0 +1,91 @@
+// Package gitea provides a client for the Gitea API.
+// ipcheck.go implements IP-level SSRF protection by checking resolved addresses
+// against known blocked CIDR ranges (RFC1918, loopback, link-local, etc.).
+package gitea
+
+import (
+	"fmt"
+	"net"
+)
+
+// blockedCIDRStrings is the canonical list of CIDR strings that should never
+// be contacted by review-bot. See IsBlockedIP for the full list of covered
+// address families.
+//
+// These are hard-coded literals: any parse failure is a programming error.
+// Validity is verified by TestBlockedCIDRsValid in ipcheck_test.go.
+var blockedCIDRStrings = []string{
+	// IPv4 loopback
+	"127.0.0.0/8",
+	// IPv4 unspecified / "this network"
+	"0.0.0.0/8",
+	// RFC1918 private ranges
+	"10.0.0.0/8",
+	"172.16.0.0/12",
+	"192.168.0.0/16",
+	// IPv4 link-local (APIPA, also used by AWS instance metadata 169.254.169.254)
+	"169.254.0.0/16",
+	// IPv4 shared address space (RFC6598, carrier-grade NAT)
+	"100.64.0.0/10",
+	// IPv4 multicast
+	"224.0.0.0/4",
+	// IPv4 reserved / broadcast
+	"240.0.0.0/4",
+	// IPv6 loopback
+	"::1/128",
+	// IPv6 unspecified
+	"::/128",
+	// IPv6 link-local
+	"fe80::/10",
+	// IPv6 unique local (ULA) — RFC4193
+	"fc00::/7",
+	// IPv6 multicast
+	"ff00::/8",
+}
+
+// blockedCIDRs is the parsed form of blockedCIDRStrings.
+// Any entry that fails to parse is recorded in blockedCIDRParseErrors instead
+// of panicking; tests verify this slice is always empty via TestBlockedCIDRsValid.
+var (
+	blockedCIDRs           []*net.IPNet
+	blockedCIDRParseErrors []string
+)
+
+func init() {
+	blockedCIDRs = make([]*net.IPNet, 0, len(blockedCIDRStrings))
+	for _, r := range blockedCIDRStrings {
+		_, cidr, err := net.ParseCIDR(r)
+		if err != nil {
+			// Record the error rather than panicking; TestBlockedCIDRsValid
+			// will catch this during tests, and the CI build will fail.
+			blockedCIDRParseErrors = append(blockedCIDRParseErrors,
+				fmt.Sprintf("ipcheck: invalid built-in CIDR %q: %v", r, err))
+			continue
+		}
+		blockedCIDRs = append(blockedCIDRs, cidr)
+	}
+}
+
+// IsBlockedIP reports whether ip is in a blocked address range.
+// It is exported for use by the validate-url subcommand and tests outside
+// this package.
+//
+// IPv6-mapped IPv4 addresses (e.g. ::ffff:192.168.1.1) are normalized to their
+// IPv4 form before checking so that IPv4 CIDRs catch them.
+//
+// Based on:
+//   - RFC1918 private ranges
+//   - RFC5735 / RFC4193 special-use IPv4/IPv6 ranges
+//   - RFC4291 IPv6 link-local / loopback
+func IsBlockedIP(ip net.IP) bool {
+	// Normalize IPv6-mapped IPv4 addresses (::ffff:x.x.x.x) to plain IPv4.
+	if v4 := ip.To4(); v4 != nil {
+		ip = v4
+	}
+	for _, cidr := range blockedCIDRs {
+		if cidr.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
@@ -0,0 +1,144 @@
+package gitea
+
+import (
+	"net"
+	"testing"
+)
+
+func TestIsBlockedIP(t *testing.T) {
+	blocked := []struct {
+		name string
+		ip   string
+	}{
+		// IPv4 loopback
+		{"loopback 127.0.0.1", "127.0.0.1"},
+		{"loopback 127.0.0.2", "127.0.0.2"},
+		{"loopback 127.255.255.255", "127.255.255.255"},
+		// IPv4 unspecified
+		{"unspecified 0.0.0.0", "0.0.0.0"},
+		{"unspecified 0.1.2.3", "0.1.2.3"},
+		// RFC1918
+		{"RFC1918 10.0.0.1", "10.0.0.1"},
+		{"RFC1918 10.255.255.255", "10.255.255.255"},
+		{"RFC1918 172.16.0.1", "172.16.0.1"},
+		{"RFC1918 172.31.255.255", "172.31.255.255"},
+		{"RFC1918 192.168.0.1", "192.168.0.1"},
+		{"RFC1918 192.168.255.255", "192.168.255.255"},
+		// Link-local (APIPA / AWS metadata)
+		{"link-local 169.254.0.1", "169.254.0.1"},
+		{"link-local 169.254.169.254", "169.254.169.254"},
+		// Shared address space (carrier-grade NAT)
+		{"CGN 100.64.0.1", "100.64.0.1"},
+		{"CGN 100.127.255.255", "100.127.255.255"},
+		// Multicast
+		{"multicast 224.0.0.1", "224.0.0.1"},
+		{"multicast 239.255.255.255", "239.255.255.255"},
+		// Reserved
+		{"reserved 240.0.0.1", "240.0.0.1"},
+		{"broadcast 255.255.255.255", "255.255.255.255"},
+		// IPv6 loopback
+		{"IPv6 loopback ::1", "::1"},
+		// IPv6 unspecified
+		{"IPv6 unspecified ::", "::"},
+		// IPv6 link-local
+		{"IPv6 link-local fe80::1", "fe80::1"},
+		{"IPv6 link-local fe80::dead:beef", "fe80::dead:beef"},
+		// IPv6 ULA
+		{"IPv6 ULA fc00::1", "fc00::1"},
+		{"IPv6 ULA fd00::1", "fd00::1"},
+		// IPv6 multicast
+		{"IPv6 multicast ff02::1", "ff02::1"},
+	}
+
+	for _, tc := range blocked {
+		t.Run(tc.name, func(t *testing.T) {
+			ip := net.ParseIP(tc.ip)
+			if ip == nil {
+				t.Fatalf("failed to parse IP %q", tc.ip)
+			}
+			if !IsBlockedIP(ip) {
+				t.Errorf("IsBlockedIP(%q) = false, want true", tc.ip)
+			}
+		})
+	}
+
+	allowed := []struct {
+		name string
+		ip   string
+	}{
+		{"public 8.8.8.8", "8.8.8.8"},
+		{"public 1.1.1.1", "1.1.1.1"},
+		{"public 198.51.100.1", "198.51.100.1"}, // RFC5737 TEST-NET-2 — a documentation-only range;
+					// not assigned to any real host, but intentionally left unblocked here because
+					// it has no special routing treatment (unlike RFC1918/loopback/link-local) and
+					// blocking it would require tracking every RFC5737 range without meaningful
+					// security benefit (no server should ever listen on a TEST-NET address).
+		{"public 151.101.1.1", "151.101.1.1"},        // Fastly
+		{"public IPv6 2001:4860:4860::8888", "2001:4860:4860::8888"}, // Google DNS
+		{"public IPv6 2606:4700:4700::1111", "2606:4700:4700::1111"}, // Cloudflare DNS
+	}
+
+	for _, tc := range allowed {
+		t.Run(tc.name, func(t *testing.T) {
+			ip := net.ParseIP(tc.ip)
+			if ip == nil {
+				t.Fatalf("failed to parse IP %q", tc.ip)
+			}
+			if IsBlockedIP(ip) {
+				t.Errorf("IsBlockedIP(%q) = true, want false", tc.ip)
+			}
+		})
+	}
+}
+
+func TestIsBlockedIPv6MappedIPv4(t *testing.T) {
+	// ::ffff:192.168.1.1 is an IPv6-mapped IPv4 address — should be blocked as RFC1918.
+	// Construct it manually as a 16-byte IP.
+	mapped := net.IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 192, 168, 1, 1}
+	if !IsBlockedIP(mapped) {
+		t.Errorf("IsBlockedIP(::ffff:192.168.1.1) = false, want true (IPv6-mapped IPv4 must be normalized)")
+	}
+
+	// ::ffff:8.8.8.8 — IPv6-mapped public IP — should be allowed.
+	mappedPublic := net.IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 8, 8, 8, 8}
+	if IsBlockedIP(mappedPublic) {
+		t.Errorf("IsBlockedIP(::ffff:8.8.8.8) = true, want false")
+	}
+}
+
+func TestIsBlockedIPEdgeCases(t *testing.T) {
+	// The boundary between RFC1918 and public ranges.
+	// 172.15.255.255 is NOT private (just below 172.16.0.0/12).
+	notPrivate := net.ParseIP("172.15.255.255")
+	if IsBlockedIP(notPrivate) {
+		t.Errorf("IsBlockedIP(172.15.255.255) = true, want false (outside 172.16.0.0/12)")
+	}
+	// 172.32.0.0 is NOT private (just above 172.31.255.255).
+	notPrivate2 := net.ParseIP("172.32.0.0")
+	if IsBlockedIP(notPrivate2) {
+		t.Errorf("IsBlockedIP(172.32.0.0) = true, want false (outside 172.16.0.0/12)")
+	}
+	// CGN: 100.63.255.255 is NOT in 100.64.0.0/10.
+	notCGN := net.ParseIP("100.63.255.255")
+	if IsBlockedIP(notCGN) {
+		t.Errorf("IsBlockedIP(100.63.255.255) = true, want false (outside 100.64.0.0/10)")
+	}
+	// CGN: 100.128.0.0 is NOT in 100.64.0.0/10.
+	notCGN2 := net.ParseIP("100.128.0.0")
+	if IsBlockedIP(notCGN2) {
+		t.Errorf("IsBlockedIP(100.128.0.0) = true, want false (outside 100.64.0.0/10)")
+	}
+}
+
+// TestBlockedCIDRsValid verifies that all entries in blockedCIDRStrings parse
+// successfully. This catches programming errors in the CIDR list without
+// requiring a startup panic. The init() function records parse failures in
+// blockedCIDRParseErrors rather than panicking; this test makes those failures
+// visible as test failures during CI.
+func TestBlockedCIDRsValid(t *testing.T) {
+	if len(blockedCIDRParseErrors) > 0 {
+		for _, msg := range blockedCIDRParseErrors {
+			t.Errorf("CIDR parse error: %s", msg)
+		}
+	}
+}
@@ -31,13 +31,13 @@ func TestPostReview_WithComments(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
+	client := NewTestClient(server.URL, "test-token")
 	comments := []ReviewComment{
 		{Path: "main.go", NewPosition: 42, Body: "[MAJOR] Something bad"},
 		{Path: "util.go", NewPosition: 10, Body: "[MINOR] Style issue"},
 	}

-	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "REQUEST_CHANGES", "summary", comments)
+	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "REQUEST_CHANGES", "summary", "", comments)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -71,8 +71,8 @@ func TestPostReview_NilComments(t *testing.T) {
 	}))
 	defer server.Close()

-	client := NewClient(server.URL, "test-token")
-	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "APPROVED", "all good", nil)
+	client := NewTestClient(server.URL, "test-token")
+	_, err := client.PostReview(context.Background(), "owner", "repo", 1, "APPROVED", "all good", "", nil)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -0,0 +1,831 @@
+// Package github provides a client for the GitHub API.
+// It supports pull request operations, file content retrieval,
+// and review submission for both github.com and GitHub Enterprise.
+package github
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	defaultBaseURL = "https://api.github.com"
+
+	// maxRetryAttempts is the number of times doRequest will attempt a request.
+	maxRetryAttempts = 3
+
+	// maxRetryAfter caps the maximum delay from a Retry-After header to prevent
+	// a server from stalling the client indefinitely.
+	maxRetryAfter = 60 * time.Second
+
+	// maxErrorBodyBytes limits how much of an error response body we read
+	// to protect against malicious servers sending unbounded data.
+	maxErrorBodyBytes = 64 * 1024 // 64 KB
+
+	// maxResponseBodyBytes limits how much of a successful response body we read
+	// for defense-in-depth against servers returning excessively large payloads.
+	maxResponseBodyBytes = 10 * 1024 * 1024 // 10 MB
+)
+
+// APIError represents an HTTP error response from the GitHub API.
+// It carries the status code so callers can distinguish between
+// different failure modes (e.g. 404 vs 500).
+//
+// The Body field stores up to 64 KiB of the raw response for programmatic
+// inspection. Error() truncates to 200 bytes for safe logging, but callers
+// should avoid logging or propagating Body directly in production since it may
+// contain sensitive details from the upstream server.
+type APIError struct {
+	StatusCode int
+	Body       string
+}
+
+func (e *APIError) Error() string {
+	body := e.Body
+	if len(body) > 200 {
+		body = body[:200] + "...(truncated)"
+	}
+	// Sanitize newlines to prevent log injection from upstream response bodies.
+	body = strings.ReplaceAll(body, "\n", " ")
+	body = strings.ReplaceAll(body, "\r", " ")
+	return fmt.Sprintf("HTTP %d: %s", e.StatusCode, body)
+}
+
+// IsNotFound reports whether an error is an API 404 response.
+func IsNotFound(err error) bool {
+	if apiErr, ok := asAPIError(err); ok {
+		return apiErr.StatusCode == http.StatusNotFound
+	}
+	return false
+}
+
+// IsUnauthorized reports whether an error is an API 401 response.
+func IsUnauthorized(err error) bool {
+	if apiErr, ok := asAPIError(err); ok {
+		return apiErr.StatusCode == http.StatusUnauthorized
+	}
+	return false
+}
+
+func asAPIError(err error) (*APIError, bool) {
+	if err == nil {
+		return nil, false
+	}
+	var target *APIError
+	if errors.As(err, &target) {
+		return target, true
+	}
+	return nil, false
+}
+
+// Client interacts with the GitHub API.
+// A Client is safe for concurrent use by multiple goroutines.
+// SetHTTPClient and SetRetryBackoff are intended for test setup only and must
+// be called before any goroutines issue requests; they have no synchronization.
+type Client struct {
+	baseURL    string
+	token      string
+	httpClient *http.Client
+
+	// allowInsecureHTTP permits requests to HTTP (non-TLS) endpoints.
+	// When false, doRequest rejects URLs with an http:// scheme.
+	allowInsecureHTTP bool
+
+	// retryBackoff defines the delays between retry attempts for 429 responses.
+	// retryBackoff[i] is the delay before attempt i+1 (after attempt i fails).
+	// If nil, defaults to {1s, 2s}.
+	retryBackoff []time.Duration
+
+	// now returns the current time. Defaults to time.Now.
+	// Override in tests to control HTTP-date Retry-After calculations.
+	now func() time.Time
+}
+
+// defaultCheckRedirect is the redirect policy used by NewClient.
+// NOTE: This function is intentionally duplicated in gitea/client.go (and vice versa)
+// because the packages are separate. Changes here must be mirrored there.
+// It rejects HTTPS->HTTP protocol downgrades (to prevent plaintext leakage)
+// and cross-host redirects (to prevent following responses from untrusted
+// endpoints). Same-host, same-or-upgraded-scheme redirects are allowed.
+func defaultCheckRedirect(req *http.Request, via []*http.Request) error {
+	if len(via) >= 10 {
+		return fmt.Errorf("stopped after 10 redirects")
+	}
+	// Guard for direct invocation in tests and any future callers;
+	// net/http guarantees len(via) >= 1 during actual redirects.
+	if len(via) == 0 {
+		return nil
+	}
+	prev := via[len(via)-1]
+	// Reject protocol downgrade: HTTPS->HTTP leaks request metadata over plaintext.
+	if prev.URL.Scheme == "https" && req.URL.Scheme == "http" {
+		return fmt.Errorf("refusing redirect: HTTPS to HTTP downgrade (%s -> %s)", prev.URL.Host, req.URL.Host)
+	}
+	// Reject cross-host redirect entirely to avoid consuming responses
+	// from untrusted endpoints.
+	if req.URL.Host != prev.URL.Host {
+		return fmt.Errorf("refusing redirect: cross-host (%s -> %s)", prev.URL.Host, req.URL.Host)
+	}
+	return nil
+}
+
+// ClientOption configures optional behavior of a Client.
+type ClientOption func(*clientConfig)
+
+type clientConfig struct {
+	allowInsecureHTTP    bool
+	insecureIsTestBypass bool
+}
+
+// AllowInsecureHTTP permits sending credentials over plaintext HTTP connections.
+// In production, this option is gated by the REVIEW_BOT_ALLOW_INSECURE=1
+// environment variable. Without the env var set, the option is ignored
+// and a warning is logged.
+//
+// For tests, use AllowInsecureHTTPForTest (defined in a _test.go file in the same package) which bypasses the env gate.
+func AllowInsecureHTTP() ClientOption {
+	return func(cfg *clientConfig) {
+		cfg.allowInsecureHTTP = true
+	}
+}
+
+// NewClient creates a new GitHub API client.
+// If baseURL is empty, it defaults to https://api.github.com.
+// For GitHub Enterprise, pass the API base URL (e.g. https://github.concur.com/api/v3).
+func NewClient(token, baseURL string, opts ...ClientOption) *Client {
+	if baseURL == "" {
+		baseURL = defaultBaseURL
+	}
+
+	var cfg clientConfig
+	for _, opt := range opts {
+		opt(&cfg)
+	}
+
+	if cfg.allowInsecureHTTP && !cfg.insecureIsTestBypass {
+		if os.Getenv("REVIEW_BOT_ALLOW_INSECURE") != "1" {
+			slog.Warn("AllowInsecureHTTP ignored: set REVIEW_BOT_ALLOW_INSECURE=1 to enable")
+			cfg.allowInsecureHTTP = false
+		} else {
+			slog.Warn("AllowInsecureHTTP enabled — credentials may be sent over plaintext",
+				"env", "REVIEW_BOT_ALLOW_INSECURE=1")
+		}
+	}
+
+	return &Client{
+		baseURL:           strings.TrimRight(baseURL, "/"),
+		token:             token,
+		allowInsecureHTTP: cfg.allowInsecureHTTP,
+		httpClient: &http.Client{
+			Timeout:       30 * time.Second,
+			CheckRedirect: defaultCheckRedirect,
+		},
+		now: time.Now,
+	}
+}
+
+// SetHTTPClient sets the underlying HTTP client used for requests.
+// This is intended for test setup only to inject mock transports; it must be
+// called before any goroutines issue requests.
+//
+// Passing nil restores the default client (30s timeout + redirect-rejecting
+// CheckRedirect policy matching NewClient).
+//
+// Callers providing a non-nil client are responsible for configuring a safe
+// CheckRedirect policy. Without one, the default net/http behavior will follow
+// redirects and may forward the Authorization header to untrusted hosts.
+func (c *Client) SetHTTPClient(hc *http.Client) {
+	if hc == nil {
+		hc = &http.Client{
+			Timeout:       30 * time.Second,
+			CheckRedirect: defaultCheckRedirect,
+		}
+	}
+	c.httpClient = hc
+}
+
+// SetRetryBackoff sets the delays between retry attempts.
+// This is intended for testing to speed up retry tests.
+//
+// Note: if an empty non-nil slice is provided, Retry-After delays parsed from
+// server responses will be computed and capped but not applied (because
+// attempt < len(backoff) is always false). This is acceptable for the
+// test-only use case but callers should be aware of this edge case.
+func (c *Client) SetRetryBackoff(backoff []time.Duration) {
+	c.retryBackoff = backoff
+}
+
+// parseRetryAfter parses a Retry-After header value, supporting both integer
+// seconds (e.g. "120") and HTTP-date format (e.g. "Thu, 01 Dec 2025 16:00:00 GMT")
+// as specified in RFC 7231 §7.1.3.
+//
+// For integer values, it returns the duration directly.
+// For HTTP-date values, it computes the delay as the difference between the
+// parsed time and now. If the date is in the past, it returns 0.
+//
+// Returns (0, false) if the value cannot be parsed as either format.
+func (c *Client) parseRetryAfter(value string) (time.Duration, bool) {
+	value = strings.TrimSpace(value)
+
+	// Try integer seconds first (most common from GitHub).
+	// RFC 7231 allows delta-seconds of 0 to indicate immediate retry.
+	if seconds, err := strconv.Atoi(value); err == nil && seconds >= 0 {
+		return time.Duration(seconds) * time.Second, true
+	}
+
+	// Try HTTP-date format (RFC 7231 §7.1.3).
+	// http.ParseTime handles RFC 1123, RFC 850, and ASCTIME formats.
+	if retryAt, err := http.ParseTime(value); err == nil {
+		delay := retryAt.Sub(c.now())
+		if delay < 0 {
+			delay = 0
+		}
+		return delay, true
+	}
+
+	return 0, false
+}
+
+// redactURL redacts sensitive components from a URL for safe inclusion in error
+// messages and log output. It removes userinfo (e.g., user:pass@) and replaces
+// query parameters with a placeholder.
+func redactURL(rawURL string) string {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return "<unparseable URL>"
+	}
+	u.User = nil
+
+	if u.RawQuery != "" {
+		u.RawQuery = "<redacted>"
+	}
+	return u.String()
+}
+
+// doRequest performs an HTTP request with retry on 429 rate limit responses.
+// It respects the Retry-After header when present, supporting both integer
+// seconds and HTTP-date formats (capped at maxRetryAfter).
+func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept string) ([]byte, error) {
+	// NOTE: This parses reqURL a second time (http.NewRequestWithContext parses it
+	// again internally). Acceptable cost: URL parsing is cheap and threading the
+	// parsed *url.URL through would complicate the interface for negligible gain.
+	if !c.allowInsecureHTTP {
+		parsed, err := url.Parse(reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("parse request URL: %w", err)
+		}
+		if strings.EqualFold(parsed.Scheme, "http") {
+			return nil, fmt.Errorf("refusing HTTP request to %s: use HTTPS or set AllowInsecureHTTP option", redactURL(reqURL))
+		}
+	}
+
+	var backoff []time.Duration
+	if c.retryBackoff != nil {
+		backoff = append([]time.Duration(nil), c.retryBackoff...)
+	} else {
+		backoff = []time.Duration{1 * time.Second, 2 * time.Second}
+	}
+
+	var lastErr error
+	for attempt := 0; attempt < maxRetryAttempts; attempt++ {
+		if attempt > 0 {
+			var delay time.Duration
+			if attempt-1 < len(backoff) {
+				delay = backoff[attempt-1]
+			}
+			if delay > 0 {
+				timer := time.NewTimer(delay)
+				select {
+				case <-timer.C:
+					timer.Stop() // no-op after fire; kept for symmetry with the ctx.Done case
+				case <-ctx.Done():
+					timer.Stop()
+					return nil, ctx.Err()
+				}
+			}
+		}
+
+		req, err := http.NewRequestWithContext(ctx, method, reqURL, nil)
+		if err != nil {
+			return nil, fmt.Errorf("create request: %w", err)
+		}
+		req.Header.Set("Authorization", "Bearer "+c.token)
+		if accept != "" {
+			req.Header.Set("Accept", accept)
+		} else {
+			req.Header.Set("Accept", "application/vnd.github+json")
+		}
+
+		resp, err := c.httpClient.Do(req)
+		if err != nil {
+			return nil, fmt.Errorf("do request: %w", err)
+		}
+
+		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+			body, err := io.ReadAll(io.LimitReader(resp.Body, maxResponseBodyBytes))
+			resp.Body.Close()
+			if err != nil {
+				return nil, fmt.Errorf("read response body: %w", err)
+			}
+			return body, nil
+		}
+
+		errBody, _ := io.ReadAll(io.LimitReader(resp.Body, maxErrorBodyBytes))
+		resp.Body.Close()
+
+		lastErr = &APIError{StatusCode: resp.StatusCode, Body: string(errBody)}
+
+		// Retry on 429 rate limit
+		if resp.StatusCode == http.StatusTooManyRequests && attempt < maxRetryAttempts-1 {
+			// Check for Retry-After header and override backoff if present.
+			// Supports both integer seconds (common) and HTTP-date format (RFC 7231).
+			if ra := resp.Header.Get("Retry-After"); ra != "" {
+				if delay, ok := c.parseRetryAfter(ra); ok {
+					if delay > maxRetryAfter {
+						delay = maxRetryAfter
+					}
+					if attempt < len(backoff) {
+						backoff[attempt] = delay
+					}
+				}
+			}
+			continue
+		}
+
+		// Don't retry other errors
+		return nil, lastErr
+	}
+
+	return nil, lastErr
+}
+
+// doGet is a convenience wrapper for GET requests with the default Accept header.
+func (c *Client) doGet(ctx context.Context, url string) ([]byte, error) {
+	return c.doRequest(ctx, http.MethodGet, url, "")
+}
+
+// doRequestWithBody performs an HTTP request with an optional body, applying the
+// same HTTPS enforcement as doRequest. It is used by write methods (POST, PUT,
+// DELETE) that bypass the retry loop in doRequest because write operations are
+// not idempotent.
+//
+// body may be nil for requests that carry no payload (e.g. DELETE).
+// When body is non-nil, Content-Type is set to application/json.
+func (c *Client) doRequestWithBody(ctx context.Context, method, reqURL string, body []byte) ([]byte, error) {
+	if !c.allowInsecureHTTP {
+		parsed, err := url.Parse(reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("parse request URL: %w", err)
+		}
+		if strings.EqualFold(parsed.Scheme, "http") {
+			return nil, fmt.Errorf("refusing HTTP request to %s: use HTTPS or set AllowInsecureHTTP option", redactURL(reqURL))
+		}
+	}
+
+	var reqBody io.Reader
+	if body != nil {
+		reqBody = bytes.NewReader(body)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, reqURL, reqBody)
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+c.token)
+	req.Header.Set("Accept", "application/vnd.github+json")
+	if body != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("do request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+		respBody, err := io.ReadAll(io.LimitReader(resp.Body, maxResponseBodyBytes))
+		if err != nil {
+			return nil, fmt.Errorf("read response body: %w", err)
+		}
+		return respBody, nil
+	}
+
+	errBody, _ := io.ReadAll(io.LimitReader(resp.Body, maxErrorBodyBytes))
+	return nil, &APIError{StatusCode: resp.StatusCode, Body: string(errBody)}
+}
+
+// --- API types ---
+
+// PullRequest holds relevant PR metadata.
+type PullRequest struct {
+	Title string `json:"title"`
+	Body  string `json:"body"`
+	Head  struct {
+		Sha string `json:"sha"`
+		Ref string `json:"ref"`
+	} `json:"head"`
+	Draft bool `json:"draft"`
+}
+
+// CommitStatus represents a single CI status entry.
+// GitHub returns "state" not "status"; this type uses Status for consistency
+// with the gitea package (both are normalized before use).
+type CommitStatus struct {
+	Status      string `json:"state"` // GitHub field is "state"
+	Context     string `json:"context"`
+	Description string `json:"description"`
+	TargetURL   string `json:"target_url"`
+}
+
+// ChangedFile represents a file modified in a PR.
+type ChangedFile struct {
+	Filename string `json:"filename"`
+	Status   string `json:"status"`
+}
+
+// ReviewComment represents an inline comment to attach to a review.
+// GitHub uses "position" (diff hunk position), whereas Gitea uses "new_position" (line number).
+// When posting inline comments on GitHub, position is required; line numbers
+// from the diff cannot be used directly.
+type ReviewComment struct {
+	ID       int64  `json:"id,omitempty"`
+	Path     string `json:"path"`
+	Position int64  `json:"position,omitempty"`   // GitHub diff hunk position
+	Line     int64  `json:"line,omitempty"`        // GitHub absolute line number (alternative to position)
+	Side     string `json:"side,omitempty"`        // "RIGHT" or "LEFT"
+	Body     string `json:"body"`
+}
+
+// Review represents a pull request review from the GitHub API.
+type Review struct {
+	ID   int64  `json:"id"`
+	Body string `json:"body"`
+	User struct {
+		Login string `json:"login"`
+	} `json:"user"`
+	State string `json:"state"`
+}
+
+// contentResponse is the GitHub contents API response for a single file.
+type contentResponse struct {
+	Name     string `json:"name"`
+	Path     string `json:"path"`
+	Type     string `json:"type"`     // "file" or "dir" or "symlink" or "submodule"
+	Content  string `json:"content"`  // Base64-encoded file content (with embedded newlines)
+	Encoding string `json:"encoding"` // "base64" or ""
+}
+
+// ContentEntry represents a file or directory entry from the contents API.
+type ContentEntry struct {
+	Name string `json:"name"`
+	Path string `json:"path"`
+	Type string `json:"type"` // "file" or "dir"
+}
+
+// --- PR methods ---
+
+// GetPullRequest fetches PR metadata.
+func (c *Client) GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("fetch PR: %w", err)
+	}
+	var pr PullRequest
+	if err := json.Unmarshal(body, &pr); err != nil {
+		return nil, fmt.Errorf("parse PR JSON: %w", err)
+	}
+	return &pr, nil
+}
+
+// GetPullRequestDiff fetches the unified diff for a PR.
+func (c *Client) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+	body, err := c.doRequest(ctx, http.MethodGet, reqURL, "application/vnd.github.diff")
+	if err != nil {
+		return "", fmt.Errorf("fetch diff: %w", err)
+	}
+	return string(body), nil
+}
+
+// GetPullRequestFiles fetches the list of files changed in a PR.
+// GitHub paginates this endpoint (100 per page max).
+func (c *Client) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]ChangedFile, error) {
+	const perPage = 100
+	var all []ChangedFile
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/files?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch PR files (page %d): %w", page, err)
+		}
+		var batch []ChangedFile
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse PR files JSON (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// GetCommitStatuses fetches CI statuses for a commit SHA.
+// GitHub has two status systems: legacy "commit statuses" and newer "check runs".
+// This method returns commit statuses only; check runs are a separate API.
+// Note: GitHub returns "state" in the JSON; CommitStatus.Status is tagged accordingly.
+func (c *Client) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]CommitStatus, error) {
+	const perPage = 100
+	var all []CommitStatus
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/commits/%s/statuses?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), url.PathEscape(sha), perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch commit statuses (page %d): %w", page, err)
+		}
+		var batch []CommitStatus
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse statuses JSON (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// --- File content methods ---
+
+// GetFileContent fetches a file from the default branch of a repo.
+// GitHub returns base64-encoded content; this method decodes it.
+func (c *Client) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return c.getFileContentAtRef(ctx, owner, repo, filepath, "")
+}
+
+// GetFileContentRef fetches a file from a specific ref (branch/tag/sha).
+func (c *Client) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return c.getFileContentAtRef(ctx, owner, repo, filepath, ref)
+}
+
+// getFileContentAtRef fetches a file at the given ref (empty = default branch).
+// GitHub's contents API returns base64-encoded file content.
+func (c *Client) getFileContentAtRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escapePath(filepath))
+	if ref != "" {
+		reqURL += "?ref=" + url.QueryEscape(ref)
+	}
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return "", fmt.Errorf("fetch file %s: %w", filepath, err)
+	}
+	var resp contentResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return "", fmt.Errorf("parse file content JSON for %s: %w", filepath, err)
+	}
+	if resp.Type != "file" {
+		return "", fmt.Errorf("path %s is a %s, not a file", filepath, resp.Type)
+	}
+	if resp.Encoding == "base64" {
+		// GitHub embeds newlines in the base64 content for readability.
+		// Strip them before decoding.
+		cleaned := strings.ReplaceAll(resp.Content, "\n", "")
+		decoded, err := base64.StdEncoding.DecodeString(cleaned)
+		if err != nil {
+			return "", fmt.Errorf("decode base64 content for %s: %w", filepath, err)
+		}
+		return string(decoded), nil
+	}
+	// Non-base64 encoding (shouldn't happen normally, but handle gracefully).
+	return resp.Content, nil
+}
+
+// ListContents lists files and directories at a given path.
+// Pass an empty path to list the repository root.
+// GitHub returns a single object (not array) when path is a file — this
+// method normalizes both cases to a slice, matching Gitea's behavior.
+func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error) {
+	var reqURL string
+	if path == "" || path == "." {
+		reqURL = fmt.Sprintf("%s/repos/%s/%s/contents",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo))
+	} else {
+		reqURL = fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escapePath(path))
+	}
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("list contents %s: %w", path, err)
+	}
+
+	var entries []ContentEntry
+	if err := json.Unmarshal(body, &entries); err != nil {
+		// GitHub returns a single object when path is a file (not an array).
+		var single contentResponse
+		if err2 := json.Unmarshal(body, &single); err2 != nil {
+			return nil, fmt.Errorf("parse contents JSON: %w", err)
+		}
+		if single.Name == "" && single.Path == "" {
+			return nil, fmt.Errorf("parse contents JSON: empty response for path %q", path)
+		}
+		entries = []ContentEntry{{
+			Name: single.Name,
+			Path: single.Path,
+			Type: single.Type,
+		}}
+	}
+	return entries, nil
+}
+
+// GetAllFilesInPath recursively fetches all file contents under a path.
+// If the path is a file, returns just that file's content.
+// If the path is a directory, recursively fetches all files within it.
+func (c *Client) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	results := make(map[string]string)
+
+	entries, err := c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		if !IsNotFound(err) {
+			return nil, fmt.Errorf("list contents %q: %w", path, err)
+		}
+		// 404 means path may be a file — try fetching directly.
+		content, fileErr := c.GetFileContent(ctx, owner, repo, path)
+		if fileErr != nil {
+			return nil, fmt.Errorf("path %q is neither a file nor directory: %w", path, fileErr)
+		}
+		results[path] = content
+		return results, nil
+	}
+
+	for _, entry := range entries {
+		switch entry.Type {
+		case "file":
+			content, err := c.GetFileContent(ctx, owner, repo, entry.Path)
+			if err != nil {
+				slog.Warn("could not fetch file from patterns repo", "file", entry.Path, "error", err)
+				continue
+			}
+			results[entry.Path] = content
+		case "dir":
+			subResults, err := c.GetAllFilesInPath(ctx, owner, repo, entry.Path)
+			if err != nil {
+				slog.Warn("could not recurse into directory", "dir", entry.Path, "error", err)
+				continue
+			}
+			for k, v := range subResults {
+				results[k] = v
+			}
+		}
+	}
+	return results, nil
+}
+
+// --- Review methods ---
+
+// PostReview submits a review to a PR.
+// event should be one of "APPROVE", "REQUEST_CHANGES", or "COMMENT".
+// commitID anchors the review to a specific commit SHA. If empty, defaults to current HEAD.
+// comments are optional inline comments; GitHub uses diff hunk position (not line numbers).
+// Note: unlike Gitea, GitHub does not support deleting submitted reviews.
+// Use COMMENT event to supersede old reviews.
+func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []ReviewComment) (*Review, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	payload := struct {
+		Body     string          `json:"body"`
+		Event    string          `json:"event"`
+		CommitID string          `json:"commit_id,omitempty"`
+		Comments []ReviewComment `json:"comments,omitempty"`
+	}{
+		Body:     body,
+		Event:    event,
+		CommitID: commitID,
+		Comments: comments,
+	}
+
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return nil, fmt.Errorf("marshal review payload: %w", err)
+	}
+
+	respBody, err := c.doRequestWithBody(ctx, http.MethodPost, reqURL, data)
+	if err != nil {
+		return nil, fmt.Errorf("post review: %w", err)
+	}
+
+	var review Review
+	if err := json.Unmarshal(respBody, &review); err != nil {
+		return nil, fmt.Errorf("parse review response: %w", err)
+	}
+	return &review, nil
+}
+
+// ListReviews returns all reviews on a pull request.
+// GitHub paginates via Link header; this method uses per_page=100.
+func (c *Client) ListReviews(ctx context.Context, owner, repo string, number int) ([]Review, error) {
+	const perPage = 100
+	var all []Review
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("list reviews (page %d): %w", page, err)
+		}
+		var batch []Review
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse reviews (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// DeleteReview attempts to delete a pull request review.
+// GitHub only allows deleting PENDING (draft) reviews. Submitted reviews cannot
+// be deleted via the API; this method returns a descriptive error in that case.
+// review-bot callers should handle this error gracefully (e.g., by not attempting
+// supersede and instead posting a new review alongside the old one).
+func (c *Client) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, reviewID)
+
+	// nil body: the GitHub DELETE endpoint for reviews requires no request body.
+	_, err := c.doRequestWithBody(ctx, http.MethodDelete, reqURL, nil)
+	if err != nil {
+		return fmt.Errorf("delete review: %w", err)
+	}
+	return nil
+}
+
+// GetAuthenticatedUser returns the login of the authenticated user.
+func (c *Client) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	reqURL := c.baseURL + "/user"
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return "", fmt.Errorf("get authenticated user: %w", err)
+	}
+	var result struct {
+		Login string `json:"login"`
+	}
+	if err := json.Unmarshal(body, &result); err != nil {
+		return "", fmt.Errorf("parse user response: %w", err)
+	}
+	return result.Login, nil
+}
+
+// RequestReviewer adds a user as a requested reviewer on a pull request.
+// This is idempotent — requesting an already-requested reviewer is a no-op.
+func (c *Client) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/requested_reviewers",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	payload := struct {
+		Reviewers []string `json:"reviewers"`
+	}{Reviewers: []string{reviewer}}
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("marshal reviewer request: %w", err)
+	}
+
+	_, err = c.doRequestWithBody(ctx, http.MethodPost, reqURL, data)
+	if err != nil {
+		return fmt.Errorf("request reviewer: %w", err)
+	}
+	return nil
+}
+
+// --- helpers ---
+
+// escapePath escapes each segment of a relative file path for use in URLs.
+// Slashes are preserved as path separators; other special characters are escaped.
+func escapePath(p string) string {
+	parts := strings.Split(p, "/")
+	for i, part := range parts {
+		parts[i] = url.PathEscape(part)
+	}
+	return strings.Join(parts, "/")
+}
@@ -0,0 +1,13 @@
+package github
+
+// AllowInsecureHTTPForTest permits sending credentials over plaintext HTTP
+// without requiring the REVIEW_BOT_ALLOW_INSECURE environment variable.
+// This is intended exclusively for test code using httptest.Server.
+//
+// Defined in a _test.go file so it is only available to test binaries.
+func AllowInsecureHTTPForTest() ClientOption {
+	return func(cfg *clientConfig) {
+		cfg.allowInsecureHTTP = true
+		cfg.insecureIsTestBypass = true
+	}
+}
@@ -16,16 +16,17 @@ import (

 // Integration test requires a running Gitea instance and LLM endpoint.
 // Set environment variables:
-//   INTEGRATION_GITEA_URL     - Gitea base URL
-//   INTEGRATION_GITEA_TOKEN   - Gitea API token with repo access
-//   INTEGRATION_GITEA_REPO    - owner/repo with an open PR
-//   INTEGRATION_PR_NUMBER     - PR number to test against
-//   INTEGRATION_LLM_BASE_URL  - LLM API base URL
-//   INTEGRATION_LLM_API_KEY   - LLM API key
-//   INTEGRATION_LLM_MODEL     - Model name
+//
+//	INTEGRATION_VCS_URL       - VCS base URL
+//	INTEGRATION_GITEA_TOKEN   - Gitea API token with repo access
+//	INTEGRATION_GITEA_REPO    - owner/repo with an open PR
+//	INTEGRATION_PR_NUMBER     - PR number to test against
+//	INTEGRATION_LLM_BASE_URL  - LLM API base URL
+//	INTEGRATION_LLM_API_KEY   - LLM API key
+//	INTEGRATION_LLM_MODEL     - Model name

 func TestIntegration_FullReviewFlow(t *testing.T) {
-	giteaURL := os.Getenv("INTEGRATION_GITEA_URL")
+	giteaURL := os.Getenv("INTEGRATION_VCS_URL")
 	giteaToken := os.Getenv("INTEGRATION_GITEA_TOKEN")
 	giteaRepo := os.Getenv("INTEGRATION_GITEA_REPO")
 	prNumStr := os.Getenv("INTEGRATION_PR_NUMBER")