fix(vcs): address PR #83 review findings (round 2)

- Extract named HeadRef and UserInfo structs from anonymous structs in PullRequest and Review (comments 16615, 16616) - Change ReviewEventApprove value from "APPROVED" to "APPROVE" to represent the action, not the state; document adapter translation responsibility (comment 16621) - Add doc comment on ReviewComment.CommitID noting optionality (16531) - Move compile-time assertion from check.go (//go:build ignore) to check_test.go with a "phase2" build tag — removes gitea adapter import from the vcs package (comment 16622) - check.go misleading comment was already fixed in prior commit (16532, 16539) - Sha→SHA, typed ReviewEvent, duplicate package doc already resolved (16537, 16538, 16530)
fix(vcs): address Phase 1 review findings
2026-05-12 12:06:29 -07:00 · 2026-05-12 12:00:30 -07:00 · 2026-05-12 10:05:39 -07:00 · 2026-05-12 10:04:57 -07:00 · 2026-05-11 10:11:13 -07:00 · 2026-05-11 09:43:51 -07:00
13 changed files with 1465 additions and 28 deletions
@@ -38,6 +38,8 @@ jobs:
          - name: security
            token_secret: SECURITY_REVIEW_TOKEN
            model: gpt-5
+            patterns_repo: rodin/security-patterns
+            patterns_files: "."
            system_prompt_file: SECURITY_REVIEW.md
    steps:
      - uses: actions/checkout@v4
@@ -60,8 +62,8 @@ jobs:
          AICORE_API_URL: ${{ secrets.AICORE_API_URL }}
          AICORE_RESOURCE_GROUP: ${{ secrets.AICORE_RESOURCE_GROUP }}
          CONVENTIONS_FILE: "CONVENTIONS.md"
-          PATTERNS_REPO: "rodin/go-patterns"
-          PATTERNS_FILES: "README.md,patterns/"
+          PATTERNS_REPO: ${{ matrix.patterns_repo || 'rodin/go-patterns' }}
+          PATTERNS_FILES: ${{ matrix.patterns_files || 'README.md,patterns/' }}
          LLM_TIMEOUT: "600"
          SYSTEM_PROMPT_FILE: ${{ matrix.system_prompt_file }}
        run: ./review-bot
@@ -0,0 +1,200 @@
+# This composite action is designed for Gitea Actions runners.
+# Gitea Actions supports GitHub Actions syntax including $GITHUB_OUTPUT,
+# actions/cache, and actions/checkout.
+# 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)'
+    required: false
+    default: ''
+  repo:
+    description: 'Repository (owner/name, defaults to current)'
+    required: false
+    default: ''
+  pr-number:
+    description: 'Pull request number (defaults to current PR)'
+    required: false
+    default: ''
+  reviewer-token:
+    description: 'Gitea token for posting the review'
+    required: true
+  reviewer-name:
+    description: 'Display name for the reviewer'
+    required: false
+    default: ''
+  llm-base-url:
+    description: 'OpenAI-compatible LLM API base URL (not required for aicore provider)'
+    required: false
+    default: ''
+  llm-api-key:
+    description: 'LLM API key (not required for aicore provider)'
+    required: false
+    default: ''
+  llm-model:
+    description: 'LLM model name'
+    required: true
+  llm-provider:
+    description: 'LLM API provider: openai, anthropic, or aicore (default openai)'
+    required: false
+    default: 'openai'
+  aicore-client-id:
+    description: 'SAP AI Core client ID (required for aicore provider)'
+    required: false
+    default: ''
+  aicore-client-secret:
+    description: 'SAP AI Core client secret (required for aicore provider)'
+    required: false
+    default: ''
+  aicore-auth-url:
+    description: 'SAP AI Core authentication URL (required for aicore provider)'
+    required: false
+    default: ''
+  aicore-api-url:
+    description: 'SAP AI Core API URL (required for aicore provider)'
+    required: false
+    default: ''
+  aicore-resource-group:
+    description: 'SAP AI Core resource group (default: default)'
+    required: false
+    default: 'default'
+  conventions-file:
+    description: 'Path to conventions file in the repo (e.g. CLAUDE.md)'
+    required: false
+    default: ''
+  patterns-repo:
+    description: 'Comma-separated repos with language patterns (e.g. rodin/elixir-patterns,rodin/phoenix-conventions)'
+    required: false
+    default: ''
+  patterns-files:
+    description: 'Comma-separated file paths or directories to fetch from patterns repos'
+    required: false
+    default: 'README.md'
+  temperature:
+    description: 'LLM temperature (0 = server default)'
+    required: false
+    default: '0'
+  timeout:
+    description: 'LLM request timeout in seconds (default 300)'
+    required: false
+    default: '300'
+  version:
+    description: 'review-bot version to install (e.g. v0.1.0, defaults to latest)'
+    required: false
+    default: 'latest'
+  dry-run:
+    description: 'Print review to stdout instead of posting'
+    required: false
+    default: 'false'
+  update-existing:
+    description: 'Delete previous review from same bot after posting new one. Accepts: true/1/yes or false/0/no (default true)'
+    required: false
+    default: 'true'
+  system-prompt-file:
+    description: 'Local file with additional system prompt instructions (e.g. security review focus)'
+    required: false
+    default: ''
+  persona:
+    description: 'Built-in persona name (security, architect, docs)'
+    required: false
+    default: ''
+  persona-file:
+    description: 'Path to custom persona JSON file'
+    required: false
+    default: ''
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Determine version
+      id: version
+      shell: bash
+      run: |
+        GITEA_URL="${{ inputs.gitea-url || github.server_url }}"
+        REPO="${{ inputs.repo || 'rodin/review-bot' }}"
+        if [ "${{ inputs.version }}" = "latest" ]; then
+          VERSION=$(curl -sSf "${GITEA_URL}/api/v1/repos/${REPO}/releases?limit=1" \
+            | python3 -c "import sys, json; releases = json.load(sys.stdin); print(releases[0]['tag_name'] if releases else '')")
+          if [ -z "$VERSION" ]; then
+            echo "Failed to determine latest version" >&2
+            exit 1
+          fi
+        else
+          VERSION="${{ inputs.version }}"
+        fi
+        echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+
+    - 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 }}
+
+    - 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="${{ steps.version.outputs.version }}"
+        BINARY="review-bot-linux-amd64"
+
+        curl -sSfL "${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"
+
+        # Verify SHA-256 checksum
+        cd "${{ runner.temp }}"
+        EXPECTED=$(grep "${BINARY}" checksums.txt | awk '{print $1}')
+        ACTUAL=$(sha256sum review-bot | awk '{print $1}')
+
+        if [ -z "$EXPECTED" ]; then
+          echo "Error: no checksum found for ${BINARY}" >&2
+          exit 1
+        fi
+        if [ "$EXPECTED" != "$ACTUAL" ]; then
+          echo "Error: checksum mismatch!" >&2
+          echo "  Expected: $EXPECTED" >&2
+          echo "  Actual:   $ACTUAL" >&2
+          exit 1
+        fi
+
+        chmod +x "${{ runner.temp }}/review-bot"
+        echo "Installed review-bot ${VERSION} (checksum verified)"
+
+    - name: Run review
+      shell: bash
+      env:
+        GITHUB_SERVER_URL: ${{ inputs.gitea-url || github.server_url }}
+        GITHUB_REPOSITORY: ${{ inputs.repo || github.repository }}
+        PR_NUMBER: ${{ inputs.pr-number || github.event.pull_request.number }}
+        REVIEWER_TOKEN: ${{ inputs.reviewer-token }}
+        REVIEWER_NAME: ${{ inputs.reviewer-name }}
+        LLM_BASE_URL: ${{ inputs.llm-base-url }}
+        LLM_API_KEY: ${{ inputs.llm-api-key }}
+        LLM_MODEL: ${{ inputs.llm-model }}
+        CONVENTIONS_FILE: ${{ inputs.conventions-file }}
+        PATTERNS_REPO: ${{ inputs.patterns-repo }}
+        PATTERNS_FILES: ${{ inputs.patterns-files }}
+        LLM_TEMPERATURE: ${{ inputs.temperature }}
+        LLM_TIMEOUT: ${{ inputs.timeout }}
+        LLM_PROVIDER: ${{ inputs.llm-provider }}
+        UPDATE_EXISTING: ${{ inputs.update-existing }}
+        SYSTEM_PROMPT_FILE: ${{ inputs.system-prompt-file }}
+        PERSONA: ${{ inputs.persona }}
+        PERSONA_FILE: ${{ inputs.persona-file }}
+        AICORE_CLIENT_ID: ${{ inputs.aicore-client-id }}
+        AICORE_CLIENT_SECRET: ${{ inputs.aicore-client-secret }}
+        AICORE_AUTH_URL: ${{ inputs.aicore-auth-url }}
+        AICORE_API_URL: ${{ inputs.aicore-api-url }}
+        AICORE_RESOURCE_GROUP: ${{ inputs.aicore-resource-group }}
+      run: |
+        ARGS=""
+        if [ "${{ inputs.dry-run }}" = "true" ]; then
+          ARGS="--dry-run"
+        fi
+        ${{ runner.temp }}/review-bot $ARGS
@@ -0,0 +1,69 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  test:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.26'
+      - run: go test ./...
+      - run: go vet ./...
+      - run: go build -o review-bot ./cmd/review-bot
+
+  # Self-review using native SAP AI Core provider
+  # Models must match SAP AI Core deployments
+  # Available models: gpt-5, anthropic--claude-4.6-sonnet, anthropic--claude-4.6-opus
+  # Removed gpt-4.1, gpt-5-mini, gpt-4.1-mini - not deployed on AI Core
+  review:
+    runs-on: ubuntu-24.04
+    if: github.event_name == 'pull_request'
+    needs: test
+    strategy:
+      matrix:
+        include:
+          - name: sonnet
+            token_secret: SONNET_REVIEW_TOKEN
+            model: anthropic--claude-4.6-sonnet
+          - name: gpt
+            token_secret: GPT_REVIEW_TOKEN
+            model: gpt-5
+          - name: security
+            token_secret: SECURITY_REVIEW_TOKEN
+            model: gpt-5
+            patterns_repo: rodin/security-patterns
+            patterns_files: "."
+            system_prompt_file: SECURITY_REVIEW.md
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.26'
+      - run: go build -o review-bot ./cmd/review-bot
+      - name: Run ${{ matrix.name }} review
+        env:
+          GITHUB_SERVER_URL: ${{ github.server_url }}
+          GITHUB_REPOSITORY: ${{ github.repository }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          REVIEWER_TOKEN: ${{ secrets[matrix.token_secret] }}
+          REVIEWER_NAME: ${{ matrix.name }}
+          LLM_PROVIDER: aicore
+          LLM_MODEL: ${{ matrix.model }}
+          AICORE_CLIENT_ID: ${{ secrets.AICORE_CLIENT_ID }}
+          AICORE_CLIENT_SECRET: ${{ secrets.AICORE_CLIENT_SECRET }}
+          AICORE_AUTH_URL: ${{ secrets.AICORE_AUTH_URL }}
+          AICORE_API_URL: ${{ secrets.AICORE_API_URL }}
+          AICORE_RESOURCE_GROUP: ${{ secrets.AICORE_RESOURCE_GROUP }}
+          CONVENTIONS_FILE: "CONVENTIONS.md"
+          PATTERNS_REPO: ${{ matrix.patterns_repo || 'rodin/go-patterns' }}
+          PATTERNS_FILES: ${{ matrix.patterns_files || 'README.md,patterns/' }}
+          LLM_TIMEOUT: "600"
+          SYSTEM_PROMPT_FILE: ${{ matrix.system_prompt_file }}
+        run: ./review-bot
@@ -0,0 +1,38 @@
+name: PR Ready Gate
+
+on:
+  pull_request:
+    types: [synchronize]
+
+jobs:
+  clear-labels:
+    runs-on: ubuntu-24.04
+    # Always run - curl commands are safe if labels don't exist
+    steps:
+      - name: Remove ready and self-reviewed labels, reassign to author
+        env:
+          GITEA_TOKEN: ${{ secrets.RODIN_TOKEN }}
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          AUTHOR=${{ github.event.pull_request.user.login }}
+          READY_LABEL_ID=38
+          SELF_REVIEWED_LABEL_ID=37
+          
+          # Remove ready label if present
+          curl -sS -X DELETE \
+            -H "Authorization: token $GITEA_TOKEN" \
+            "https://gitea.weiker.me/api/v1/repos/${{ github.repository }}/issues/${PR_NUMBER}/labels/${READY_LABEL_ID}" || true
+          
+          # Remove self-reviewed label if present
+          curl -sS -X DELETE \
+            -H "Authorization: token $GITEA_TOKEN" \
+            "https://gitea.weiker.me/api/v1/repos/${{ github.repository }}/issues/${PR_NUMBER}/labels/${SELF_REVIEWED_LABEL_ID}" || true
+          
+          # Reassign to author
+          curl -sS -X PATCH \
+            -H "Authorization: token $GITEA_TOKEN" \
+            -H "Content-Type: application/json" \
+            -d "{\"assignees\": [\"${AUTHOR}\"]}" \
+            "https://gitea.weiker.me/api/v1/repos/${{ github.repository }}/pulls/${PR_NUMBER}"
+          
+          echo "Cleared ready/self-reviewed labels and reassigned PR #${PR_NUMBER} to ${AUTHOR}"
@@ -0,0 +1,97 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  release:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.26'
+
+      - name: Run tests
+        run: |
+          go vet ./...
+          go test ./...
+
+      - name: Build binaries
+        run: |
+          VERSION=${GITHUB_REF_NAME}
+          mkdir -p dist
+
+          GOOS=linux GOARCH=amd64 go build -ldflags "-s -w -X main.version=${VERSION}" -o dist/review-bot-linux-amd64 ./cmd/review-bot
+          GOOS=linux GOARCH=arm64 go build -ldflags "-s -w -X main.version=${VERSION}" -o dist/review-bot-linux-arm64 ./cmd/review-bot
+          GOOS=darwin GOARCH=amd64 go build -ldflags "-s -w -X main.version=${VERSION}" -o dist/review-bot-darwin-amd64 ./cmd/review-bot
+          GOOS=darwin GOARCH=arm64 go build -ldflags "-s -w -X main.version=${VERSION}" -o dist/review-bot-darwin-arm64 ./cmd/review-bot
+
+          cd dist && sha256sum * > checksums.txt
+
+      - name: Create release and upload assets
+        env:
+          GITEA_TOKEN: ${{ secrets.RELEASE_TOKEN }}
+        run: |
+          VERSION=${GITHUB_REF_NAME}
+          GITEA_URL="${{ github.server_url }}"
+          REPO="${{ github.repository }}"
+
+          # Create release (or find existing one for this tag)
+          HTTP_CODE=$(curl -s -o /tmp/release_response.json -w "%{http_code}" -X POST \
+            -H "Authorization: token ${GITEA_TOKEN}" \
+            -H "Content-Type: application/json" \
+            "${GITEA_URL}/api/v1/repos/${REPO}/releases" \
+            -d "{\"tag_name\": \"${VERSION}\", \"name\": \"${VERSION}\", \"body\": \"Release ${VERSION}\", \"draft\": false, \"prerelease\": false}")
+
+          if [ "$HTTP_CODE" = "409" ]; then
+            echo "Release for ${VERSION} already exists, fetching existing..."
+            curl -sSf -o /tmp/release_response.json \
+              -H "Authorization: token ${GITEA_TOKEN}" \
+              "${GITEA_URL}/api/v1/repos/${REPO}/releases/tags/${VERSION}"
+          elif [ "$HTTP_CODE" != "201" ]; then
+            echo "Failed to create release (HTTP ${HTTP_CODE})" >&2
+            cat /tmp/release_response.json >&2
+            exit 1
+          fi
+
+          # Parse release ID (python3 available on ubuntu-24.04 runners)
+          RELEASE_ID=$(python3 -c "import json; print(json.load(open('/tmp/release_response.json'))['id'])")
+
+          if [ -z "$RELEASE_ID" ]; then
+            echo "Failed to parse release ID" >&2
+            cat /tmp/release_response.json >&2
+            exit 1
+          fi
+
+          echo "Release ID: ${RELEASE_ID}"
+
+          # Upload each asset (idempotent: delete existing asset with same name first)
+          for file in dist/*; do
+            filename=$(basename "$file")
+            echo "Uploading ${filename}..."
+
+            # Check if asset already exists and delete it
+            EXISTING_ID=$(export ASSET_NAME="${filename}"; curl -sS \
+              -H "Authorization: token ${GITEA_TOKEN}" \
+              "${GITEA_URL}/api/v1/repos/${REPO}/releases/${RELEASE_ID}/assets" \
+              | python3 -c "import json,sys,os; name=os.environ['ASSET_NAME']; assets=json.load(sys.stdin); print(next((str(a['id']) for a in assets if a['name']==name),''))" 2>/dev/null)
+
+            if [ -n "$EXISTING_ID" ]; then
+              echo "  Asset ${filename} already exists (id=${EXISTING_ID}), deleting..."
+              curl -sSf -X DELETE \
+                -H "Authorization: token ${GITEA_TOKEN}" \
+                "${GITEA_URL}/api/v1/repos/${REPO}/releases/${RELEASE_ID}/assets/${EXISTING_ID}"
+            fi
+
+            curl -sSf -X POST \
+              -H "Authorization: token ${GITEA_TOKEN}" \
+              -H "Content-Type: application/octet-stream" \
+              "${GITEA_URL}/api/v1/repos/${REPO}/releases/${RELEASE_ID}/assets?name=$(printf '%s' "${filename}" | jq -sRr @uri)" \
+              --data-binary "@${file}"
+          done
+
+          echo "Release ${VERSION} created with assets"
@@ -329,11 +329,12 @@ All flags have environment variable equivalents:
 ### Token Scopes Required

 | Scope | Purpose |
-|-------|---------|
+|-------|--------|
 | `write:issue` | Post and delete reviews |
 | `write:repository` | Read PR diffs, file content, commit statuses |
+| `read:user` | Self-request as reviewer (optional but recommended) |

-No `read:user` scope needed — the bot identifies itself from the review response.
+Without `read:user`, the bot still works but cannot add itself to the PR's reviewer list.

 ## Development

@@ -54,8 +54,8 @@ func main() {
 	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")
-	repo := flag.String("repo", envOrDefault("GITEA_REPO", ""), "Repository (owner/name)")
+	giteaURL := flag.String("gitea-url", envOrDefault("GITEA_URL", envOrDefault("GITHUB_SERVER_URL", "")), "Gitea instance URL")
+	repo := flag.String("repo", envOrDefault("GITEA_REPO", envOrDefault("GITHUB_REPOSITORY", "")), "Repository (owner/name)")
 	prNum := flag.String("pr", envOrDefault("PR_NUMBER", ""), "Pull request number")
 	reviewerName := flag.String("reviewer-name", envOrDefault("REVIEWER_NAME", ""), "Reviewer display name")
 	reviewerToken := flag.String("reviewer-token", envOrDefault("REVIEWER_TOKEN", ""), "Gitea token for posting review")
@@ -544,6 +544,9 @@ func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patt
 		}
 		owner, repo := parts[0], parts[1]

+		var repoLoadedFiles []string
+		var repoSkippedFiles []string
+
 		for _, path := range paths {
 			path = strings.TrimSpace(path)
 			if path == "" {
@@ -559,11 +562,22 @@ func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patt
 			for filePath, content := range files {
 				// Only include markdown and text files as patterns
 				if !isPatternFile(filePath) {
+					repoSkippedFiles = append(repoSkippedFiles, filePath)
 					continue
 				}
+				repoLoadedFiles = append(repoLoadedFiles, filePath)
 				sb.WriteString(fmt.Sprintf("### %s/%s\n\n%s\n\n", repoRef, filePath, content))
 			}
 		}
+
+		if len(repoLoadedFiles) > 0 {
+			slog.Info("loaded pattern files", "repo", repoRef, "count", len(repoLoadedFiles), "files", repoLoadedFiles)
+		} else {
+			slog.Warn("no pattern files loaded", "repo", repoRef, "paths", paths)
+		}
+		if len(repoSkippedFiles) > 0 {
+			slog.Debug("skipped non-pattern files", "repo", repoRef, "count", len(repoSkippedFiles), "files", repoSkippedFiles)
+		}
 	}
 	return sb.String()
 }
@@ -0,0 +1,268 @@
+# GitHub Support for review-bot
+
+## Goal
+
+AI code reviews on GitHub PRs using SAP AI Core as the LLM provider.
+
+## Non-Goals
+
+- Auto-detection of platform (explicit `--provider` flag is fine)
+- Unifying into one abstraction layer for its own sake
+
+## Constraints
+
+1. **Same features on both platforms** — anything review-bot does on Gitea should work on GitHub
+2. **Testable** — small interfaces, dependency injection, no global state
+3. **Interface from working code** — extract from gitea/, don't invent in vacuum
+
+---
+
+## Part 1: Feature Inventory
+
+What does review-bot actually do?
+
+### Core Review Flow
+
+| Feature | Description |
+|---------|-------------|
+| Get PR metadata | Title, body, head SHA, base ref |
+| Get PR diff | Unified diff format |
+| Get PR files | List of changed files with status |
+| Get file content | Raw file at ref |
+| List directory | Enumerate files in path |
+| Post review | Body + inline comments + verdict |
+
+### Review Management
+
+| Feature | Description |
+|---------|-------------|
+| List reviews | Get existing reviews on PR |
+| Delete review | Remove old review before re-posting |
+| Get authenticated user | Who am I? |
+
+### Platform-Specific (not in shared interface)
+
+| Feature | Gitea | GitHub |
+|---------|-------|--------|
+| Resolve comment | Yes | No equivalent |
+| Timeline API | Yes | No equivalent |
+
+These stay on gitea.Client directly. Callers that need them type-assert.
+
+---
+
+## Part 2: GitHub API Mapping
+
+| Feature | Gitea API | GitHub API |
+|---------|-----------|------------|
+| Get PR | `GET /api/v1/repos/.../pulls/{n}` | `GET /repos/.../pulls/{n}` |
+| Get diff | `.diff` suffix | `Accept: application/vnd.github.diff` header |
+| Get files | `GET .../pulls/{n}/files` | Same |
+| Get file content | `GET .../raw/{path}?ref=` | `GET .../contents/{path}?ref=` + base64 decode |
+| List directory | `GET .../contents/{path}` | Same |
+| Post review | `POST .../pulls/{n}/reviews` | Same (adapter handles comment schema) |
+| List reviews | `GET .../pulls/{n}/reviews` | Same |
+| Delete review | `DELETE .../pulls/{n}/reviews/{id}` | Same |
+| Get user | `GET /api/v1/user` | `GET /user` |
+
+---
+
+## Part 3: Interface Design
+
+**Principle:** Extract from working gitea/ code. The interface is discovered, not invented.
+
+### Small, role-based interfaces
+
+```go
+// vcs/interfaces.go
+
+type PRReader interface {
+    GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error)
+    GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
+    GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]ChangedFile, error)
+}
+
+type FileReader interface {
+    GetFileContent(ctx context.Context, owner, repo, path, ref string) (string, error)
+    ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error)
+}
+
+type Reviewer interface {
+    PostReview(ctx context.Context, owner, repo string, number int, req ReviewRequest) (*Review, error)
+    ListReviews(ctx context.Context, owner, repo string, number int) ([]Review, error)
+    DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
+}
+
+type Identity interface {
+    GetAuthenticatedUser(ctx context.Context) (string, error)
+}
+
+// Client combines all for callers that need everything
+type Client interface {
+    PRReader
+    FileReader
+    Reviewer
+    Identity
+}
+```
+
+### Types
+
+Use what gitea/ already has. Move to vcs/types.go or re-export.
+
+```go
+type PullRequest struct { ... }   // from gitea.PullRequest
+type ChangedFile struct { ... }   // from gitea.ChangedFile
+type ContentEntry struct { ... }  // from gitea.ContentEntry
+type Review struct { ... }        // from gitea.Review
+type ReviewRequest struct { ... } // new, for PostReview input
+type ReviewComment struct { ... } // from gitea.ReviewComment
+```
+
+### Adapter responsibilities
+
+Each adapter (gitea, github) handles:
+- API URL construction
+- Auth header format (`token` vs `Bearer`)
+- Request/response mapping
+- Comment schema translation (line numbers, commit IDs, etc.)
+
+---
+
+## Part 4: Test Plan
+
+### Unit Tests (mock HTTP)
+
+```
+github/
+  pr_test.go        # TestGetPullRequest, TestGetDiff, TestGetFiles
+  files_test.go     # TestGetFileContent, TestListContents
+  review_test.go    # TestPostReview, TestListReviews, TestDeleteReview
+  identity_test.go  # TestGetAuthenticatedUser
+```
+
+Per method: happy path, 404, 401, 429, malformed response.
+
+### Integration Tests
+
+Against github.com/aweiker/ai-core-review-bot:
+- Fetch real PR
+- Fetch real file
+- Post + delete review (clean up)
+
+### End-to-End
+
+Open PR on test repo, run full review-bot, verify review appears.
+
+---
+
+## Part 5: Implementation Phases
+
+### Phase 1: Extract interfaces from gitea/
+
+**Work:**
+- Create `vcs/interfaces.go` with interfaces extracted from gitea/client.go signatures
+- Create `vcs/types.go` — move or alias types from gitea/
+- Verify gitea.Client satisfies vcs.Client (compile-time check)
+
+**Exit criteria:** `var _ vcs.Client = (*gitea.Client)(nil)` compiles.
+
+---
+
+### Phase 2: Gitea adapter (if needed)
+
+**Work:**
+- If gitea.Client method signatures don't match exactly, create wrapper
+- Keep gitea/ working exactly as before
+
+**Exit criteria:** Existing tests pass. No behavior change.
+
+---
+
+### Phase 3: GitHub client — PRReader
+
+**Work:**
+- `github/client.go` — struct, constructor, HTTP helpers
+- `github/pr.go` — GetPullRequest, GetPullRequestDiff, GetPullRequestFiles
+- Unit tests
+
+**Exit criteria:** `go test ./github/...` passes for PR methods.
+
+---
+
+### Phase 4: GitHub client — FileReader
+
+**Work:**
+- `github/files.go` — GetFileContent, ListContents
+- Unit tests
+
+**Exit criteria:** Unit tests pass.
+
+---
+
+### Phase 5: GitHub client — Reviewer + Identity
+
+**Work:**
+- `github/review.go` — PostReview, ListReviews, DeleteReview
+- `github/identity.go` — GetAuthenticatedUser
+- Unit tests
+
+**Exit criteria:** Unit tests pass.
+
+---
+
+### Phase 6: Integration tests
+
+**Work:**
+- `integration/github_test.go`
+- Test against real GitHub
+
+**Exit criteria:** All integration tests pass.
+
+---
+
+### Phase 7: Wire into cmd/review-bot
+
+**Work:**
+- Add `--provider github|gitea` flag (default: gitea for backward compat)
+- Select client based on flag
+- Update to use vcs interfaces where it makes sense
+
+**Exit criteria:**
+- `./review-bot --provider github ...` works
+- `./review-bot --provider gitea ...` works (same as before)
+- Existing Gitea workflows unchanged
+
+---
+
+### Phase 8: GitHub Actions workflow + releases
+
+**Work:**
+- `.github/workflows/ci.yml` — test on PR
+- `.github/workflows/release.yml` — publish binary to GitHub releases
+- `.github/actions/review/action.yml` — composite action
+- Action downloads binary from github.com/aweiker/ai-core-review-bot releases
+
+**Exit criteria:** 
+- CI runs on github.com/aweiker/ai-core-review-bot
+- Release creates downloadable binary
+- Review action posts review successfully
+
+---
+
+## Part 6: Decisions
+
+| Question | Decision |
+|----------|----------|
+| Auth token | Workflow `GITHUB_TOKEN` (automatic) |
+| Binary distribution | GitHub releases on aweiker/ai-core-review-bot |
+| Comment schema | Adapter's job — translate ReviewComment to platform format |
+| Default provider | `gitea` for backward compatibility |
+| Shared types | vcs/types.go (extracted from gitea/) |
+| Platform-specific features | Stay on concrete client, not interface |
+
+---
+
+## Summary
+
+8 phases. Start by extracting interfaces from working gitea/ code, not inventing them. GitHub implements the same interfaces. Each phase has clear exit criteria.
@@ -11,9 +11,11 @@ import (
 	"fmt"
 	"io"
 	"log/slog"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
+	"syscall"
 	"time"
 )

@@ -39,12 +41,26 @@ func IsNotFound(err error) bool {
 	return errors.As(err, &apiErr) && apiErr.StatusCode == http.StatusNotFound
 }

+// IsServerError reports whether an error is an API 5xx response.
+func IsServerError(err error) bool {
+	var apiErr *APIError
+	return errors.As(err, &apiErr) && apiErr.StatusCode >= 500 && apiErr.StatusCode < 600
+}
+
 // Client interacts with the Gitea API.
 // A Client is safe for concurrent use by multiple goroutines.
 type Client struct {
 	baseURL string
 	token   string
 	http    *http.Client
+
+	// RetryBackoff defines the delays between retry attempts.
+	// RetryBackoff[i] is the delay before attempt i+1 (after attempt i fails).
+	// If nil, defaults to {1s, 2s}. Set to shorter durations in tests.
+	//
+	// This field must be configured before the first request is made.
+	// Modifying it while requests are in flight is not safe.
+	RetryBackoff []time.Duration
 }

 // NewClient creates a new Gitea API client.
@@ -56,6 +72,12 @@ func NewClient(baseURL, token string) *Client {
 	}
 }

+// SetHTTPClient sets the underlying HTTP client used for requests.
+// This is intended for testing to inject mock transports.
+func (c *Client) SetHTTPClient(hc *http.Client) {
+	c.http = hc
+}
+
 // PullRequest holds relevant PR metadata.
 type PullRequest struct {
 	Title string `json:"title"`
@@ -210,24 +232,185 @@ func (c *Client) PostReview(ctx context.Context, owner, repo string, number int,
 	return &review, nil
 }

+// isTemporaryNetError reports whether err is a temporary network error worth retrying.
+// This includes connection refused, network unreachable, connection reset, and DNS
+// timeouts. It explicitly excludes permanent errors like permission denied or
+// "no such host" DNS failures.
+func isTemporaryNetError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	// Check for OpError and inspect the underlying syscall error.
+	// Not all OpErrors are transient — permission denied, for example, is permanent.
+	var opErr *net.OpError
+	if errors.As(err, &opErr) {
+		return isRetriableSyscallError(opErr.Err)
+	}
+
+	// DNS errors: only retry on timeout, not on "no such host" which is permanent.
+	var dnsErr *net.DNSError
+	if errors.As(err, &dnsErr) {
+		return dnsErr.IsTimeout
+	}
+
+	// Check for net.Error with Timeout() (Temporary is deprecated)
+	var netErr net.Error
+	if errors.As(err, &netErr) {
+		return netErr.Timeout()
+	}
+
+	return false
+}
+
+// isRetriableSyscallError reports whether the underlying error from a net.OpError
+// is a transient syscall error worth retrying.
+func isRetriableSyscallError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	// Check for syscall.Errno directly or wrapped
+	var errno syscall.Errno
+	if errors.As(err, &errno) {
+		switch errno {
+		case syscall.ECONNREFUSED, // connection refused — server not listening
+			syscall.ECONNRESET,   // connection reset by peer
+			syscall.ENETUNREACH,  // network unreachable
+			syscall.EHOSTUNREACH, // host unreachable
+			syscall.ETIMEDOUT:    // connection timed out
+			return true
+		default:
+			// EACCES, EPERM, etc. are permanent — don't retry
+			return false
+		}
+	}
+
+	// If we can't identify the specific syscall error, be conservative and retry.
+	// This handles wrapped errors or platform-specific error types.
+	// The retry count is limited, so erring on the side of retrying is safe.
+	return true
+}
+
+// redactURL strips query parameters from a URL for safe logging.
+// This prevents accidental exposure of sensitive data that future callers
+// might pass via query strings.
+func redactURL(rawURL string) string {
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		// If we cannot parse it, return a safe placeholder rather than
+		// potentially logging something sensitive.
+		return "[invalid URL]"
+	}
+	if parsed.RawQuery != "" {
+		parsed.RawQuery = "[redacted]"
+	}
+	return parsed.String()
+}
+
+// sanitizeErrorForLog returns a loggable version of an error that omits
+// potentially sensitive content like response bodies. For APIError, only
+// the status code is included; for other errors, the type is preserved.
+func sanitizeErrorForLog(err error) string {
+	if err == nil {
+		return "<nil>"
+	}
+	var apiErr *APIError
+	if errors.As(err, &apiErr) {
+		return fmt.Sprintf("HTTP %d", apiErr.StatusCode)
+	}
+	return err.Error()
+}
+
+// doGet performs an HTTP GET request with retry on 5xx errors and temporary
+// network errors. Retries up to 3 times with exponential backoff (1s, 2s delays
+// by default; configurable via Client.RetryBackoff for testing).
 func (c *Client) doGet(ctx context.Context, reqURL string) ([]byte, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
-	if err != nil {
-		return nil, err
+	const maxAttempts = 3
+	// backoff[i] is the delay before attempt i+1 (i.e., after attempt i fails).
+	// First attempt (i=0) has no delay; retries wait 1s then 2s by default.
+	backoff := c.RetryBackoff
+	if backoff == nil {
+		backoff = []time.Duration{1 * time.Second, 2 * time.Second}
 	}
-	req.Header.Set("Authorization", "token "+c.token)

-	resp, err := c.http.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
+	// maxErrorBodyBytes limits how much of an error response body we read
+	// to protect against malicious servers sending unbounded data.
+	const maxErrorBodyBytes = 64 * 1024 // 64 KB

-	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-		body, _ := io.ReadAll(resp.Body)
-		return nil, &APIError{StatusCode: resp.StatusCode, Body: string(body)}
+	var lastErr error
+	for attempt := 0; attempt < maxAttempts; attempt++ {
+		if attempt > 0 {
+			// Determine delay: use backoff slice if available, otherwise retry immediately.
+			// An empty RetryBackoff slice means "retry without delay" — this is intentional
+			// as the caller explicitly configured no delays.
+			var delay time.Duration
+			if attempt-1 < len(backoff) {
+				delay = backoff[attempt-1]
+			}
+
+			if delay > 0 {
+				slog.Warn("retrying request after error",
+					"attempt", attempt+1,
+					"url", redactURL(reqURL),
+					"delay", delay.String(),
+					"lastError", sanitizeErrorForLog(lastErr))
+
+				timer := time.NewTimer(delay)
+				select {
+				case <-timer.C:
+				case <-ctx.Done():
+					timer.Stop()
+					return nil, ctx.Err()
+				}
+			}
+		}
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
+		if err != nil {
+			return nil, err
+		}
+		req.Header.Set("Authorization", "token "+c.token)
+
+		resp, err := c.http.Do(req)
+		if err != nil {
+			// Always capture the error for consistent return at loop end.
+			// This ensures both network errors and HTTP 5xx return lastErr.
+			lastErr = err
+
+			// Only retry temporary network errors when attempts remain.
+			if attempt < maxAttempts-1 && isTemporaryNetError(err) {
+				slog.Warn("temporary network error, will retry",
+					"attempt", attempt+1,
+					"url", redactURL(reqURL),
+					"error", err)
+				continue
+			}
+			// Non-retryable network error or final attempt exhausted.
+			return nil, lastErr
+		}
+		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+			body, err := io.ReadAll(resp.Body)
+			resp.Body.Close()
+			if err != nil {
+				return nil, err
+			}
+			return body, nil
+		}
+
+		// Error path: limit how much we read from potentially malicious server
+		errBody, _ := io.ReadAll(io.LimitReader(resp.Body, maxErrorBodyBytes))
+		resp.Body.Close()
+
+		lastErr = &APIError{StatusCode: resp.StatusCode, Body: string(errBody)}
+
+		// Only retry on 5xx server errors
+		if resp.StatusCode < 500 || resp.StatusCode >= 600 {
+			return nil, lastErr
+		}
 	}
-	return io.ReadAll(resp.Body)
+
+	return nil, lastErr
 }

 // escapePath escapes each segment of a relative file path for use in URLs.
@@ -251,7 +434,13 @@ type ContentEntry struct {

 // ListContents lists files and directories at a given path in a repo.
 // Pass an empty path to list the repository root.
+// If the path points to a file (not a directory), Gitea returns a single
+// object instead of an array; this method normalizes both cases to a slice.
 func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error) {
+	// Normalize "." to empty string — Gitea API rejects "." with 500
+	if path == "." {
+		path = ""
+	}
 	var reqURL string
 	if path == "" {
 		reqURL = fmt.Sprintf("%s/api/v1/repos/%s/%s/contents", c.baseURL, url.PathEscape(owner), url.PathEscape(repo))
@@ -264,7 +453,16 @@ func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]
 	}
 	var entries []ContentEntry
 	if err := json.Unmarshal(body, &entries); err != nil {
-		return nil, fmt.Errorf("parse contents JSON: %w", err)
+		// Gitea returns a single object (not an array) when path is a file
+		var single ContentEntry
+		if err2 := json.Unmarshal(body, &single); err2 != nil {
+			return nil, fmt.Errorf("parse contents JSON: %w", err)
+		}
+		// Guard against empty/malformed responses
+		if single.Name == "" && single.Path == "" {
+			return nil, fmt.Errorf("parse contents JSON: empty response for path %q", path)
+		}
+		entries = []ContentEntry{single}
 	}
 	return entries, nil
 }
@@ -317,9 +515,9 @@ func (c *Client) GetAllFilesInPath(ctx context.Context, owner, repo, path string

 // Review represents a pull request review from the Gitea API.
 type Review struct {
-	ID       int64  `json:"id"`
-	Body     string `json:"body"`
-	User     struct {
+	ID   int64  `json:"id"`
+	Body string `json:"body"`
+	User struct {
 		Login string `json:"login"`
 	} `json:"user"`
 	State    string `json:"state"`
@@ -6,10 +6,14 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"strings"
+	"sync/atomic"
+	"syscall"
 	"testing"
+	"time"
 )

 func TestGetPullRequest(t *testing.T) {
@@ -276,11 +280,64 @@ func TestListContents(t *testing.T) {
 	}
 }

+func TestListContents_DotPath(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// "." should be normalized to empty path, which hits the root contents endpoint
+		if r.URL.Path != "/api/v1/repos/owner/repo/contents" {
+			t.Errorf("expected root contents path, got: %s", r.URL.Path)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprintf(w, `[{"name":"README.md","path":"README.md","type":"file"}]`)
+	}))
+	defer server.Close()
+
+	client := NewClient(server.URL, "test-token")
+	entries, err := client.ListContents(context.Background(), "owner", "repo", ".")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("expected 1 entry, got %d", len(entries))
+	}
+	if entries[0].Name != "README.md" {
+		t.Errorf("expected README.md, got %s", entries[0].Name)
+	}
+}
+
+func TestListContents_FilePath(t *testing.T) {
+	// Gitea returns a single object (not an array) when path is a file
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/v1/repos/owner/repo/contents/README.md" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		// Single object, not an array
+		fmt.Fprintf(w, `{"name":"README.md","path":"README.md","type":"file"}`)
+	}))
+	defer server.Close()
+
+	client := NewClient(server.URL, "test-token")
+	entries, err := client.ListContents(context.Background(), "owner", "repo", "README.md")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("expected 1 entry, got %d", len(entries))
+	}
+	if entries[0].Name != "README.md" {
+		t.Errorf("expected README.md, got %s", entries[0].Name)
+	}
+	if entries[0].Type != "file" {
+		t.Errorf("expected type file, got %s", entries[0].Type)
+	}
+}
+
 func TestGetAllFilesInPath_File(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path == "/api/v1/repos/owner/repo/contents/README.md" {
-			// Gitea returns 404 for contents API on files (it's not a dir)
-			http.NotFound(w, r)
+			// Gitea returns a single object (not array) when path is a file
+			w.Header().Set("Content-Type", "application/json")
+			fmt.Fprintf(w, `{"name":"README.md","path":"README.md","type":"file"}`)
 			return
 		}
 		if r.URL.Path == "/api/v1/repos/owner/repo/raw/README.md" {
@@ -584,9 +641,9 @@ func TestGetAllFilesInPath_403Propagates(t *testing.T) {

 func TestIsNotFound(t *testing.T) {
 	tests := []struct {
-		name   string
-		err    error
-		want   bool
+		name string
+		err  error
+		want bool
 	}{
 		{"nil error", nil, false},
 		{"non-API error", fmt.Errorf("network timeout"), false},
@@ -743,3 +800,347 @@ func TestResolveComment_Error(t *testing.T) {
 		t.Fatal("expected error for 404 response")
 	}
 }
+
+func TestIsServerError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{"nil error", nil, false},
+		{"non-API error", fmt.Errorf("network timeout"), false},
+		{"404 APIError", &APIError{StatusCode: 404, Body: "not found"}, false},
+		{"500 APIError", &APIError{StatusCode: 500, Body: "server error"}, true},
+		{"502 APIError", &APIError{StatusCode: 502, Body: "bad gateway"}, true},
+		{"503 APIError", &APIError{StatusCode: 503, Body: "unavailable"}, true},
+		{"599 APIError", &APIError{StatusCode: 599, Body: "edge case"}, true},
+		{"600 not server error", &APIError{StatusCode: 600, Body: "edge"}, false},
+		{"400 not server error", &APIError{StatusCode: 400, Body: "bad request"}, false},
+		{"wrapped 500", fmt.Errorf("fetch: %w", &APIError{StatusCode: 500, Body: "err"}), true},
+		{"wrapped 404", fmt.Errorf("fetch: %w", &APIError{StatusCode: 404, Body: "err"}), false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := IsServerError(tt.err)
+			if got != tt.want {
+				t.Errorf("IsServerError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestDoGet_RetriesOn500(t *testing.T) {
+	attempts := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts < 3 {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte(`{"message":"transient error"}`))
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"data":"success"}`))
+	}))
+	defer server.Close()
+
+	client := NewClient(server.URL, "test-token")
+	// Use short backoff for fast tests
+	client.RetryBackoff = []time.Duration{1 * time.Millisecond, 1 * time.Millisecond}
+
+	body, err := client.doGet(context.Background(), server.URL+"/test")
+	if err != nil {
+		t.Fatalf("expected success after retry, got error: %v", err)
+	}
+	if string(body) != `{"data":"success"}` {
+		t.Errorf("body = %q, want %q", string(body), `{"data":"success"}`)
+	}
+	if attempts != 3 {
+		t.Errorf("attempts = %d, want 3", attempts)
+	}
+}
+
+func TestDoGet_FailsAfterMaxRetries(t *testing.T) {
+	attempts := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(`{"message":"persistent error"}`))
+	}))
+	defer server.Close()
+
+	client := NewClient(server.URL, "test-token")
+	// Use short backoff for fast tests
+	client.RetryBackoff = []time.Duration{1 * time.Millisecond, 1 * time.Millisecond}
+
+	_, err := client.doGet(context.Background(), server.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error after max retries")
+	}
+	var apiErr *APIError
+	if !errors.As(err, &apiErr) {
+		t.Fatalf("expected APIError, got: %v", err)
+	}
+	if apiErr.StatusCode != http.StatusInternalServerError {
+		t.Errorf("status = %d, want 500", apiErr.StatusCode)
+	}
+	if attempts != 3 {
+		t.Errorf("attempts = %d, want 3 (max retries)", attempts)
+	}
+}
+
+func TestDoGet_NoRetryOn4xx(t *testing.T) {
+	attempts := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(http.StatusForbidden)
+		w.Write([]byte(`{"message":"forbidden"}`))
+	}))
+	defer server.Close()
+
+	client := NewClient(server.URL, "test-token")
+	_, err := client.doGet(context.Background(), server.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error for 403")
+	}
+	var apiErr *APIError
+	if !errors.As(err, &apiErr) {
+		t.Fatalf("expected APIError, got: %v", err)
+	}
+	if apiErr.StatusCode != http.StatusForbidden {
+		t.Errorf("status = %d, want 403", apiErr.StatusCode)
+	}
+	if attempts != 1 {
+		t.Errorf("attempts = %d, want 1 (no retry on 4xx)", attempts)
+	}
+}
+
+func TestDoGet_RespectsContextCancellation(t *testing.T) {
+	attempts := 0
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(`{"message":"error"}`))
+	}))
+	defer server.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	client := NewClient(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}
+
+	// Cancel after first attempt returns and retry begins
+	go func() {
+		time.Sleep(20 * time.Millisecond)
+		cancel()
+	}()
+
+	_, err := client.doGet(ctx, server.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error on context cancellation")
+	}
+	// Should have made 1 attempt, then context cancelled during backoff
+	if attempts != 1 {
+		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 {
+	failCount    int32 // number of failures remaining (atomic)
+	failErr      error // error to return on failure
+	realServer   *httptest.Server
+	attemptsMade atomic.Int32 // tracks total attempts
+}
+
+func (m *mockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	m.attemptsMade.Add(1)
+	remaining := atomic.AddInt32(&m.failCount, -1)
+	if remaining >= 0 {
+		// Still have failures to return
+		return nil, m.failErr
+	}
+	// Redirect to real server
+	req.URL.Host = m.realServer.Listener.Addr().String()
+	req.URL.Scheme = "http"
+	return http.DefaultTransport.RoundTrip(req)
+}
+
+func TestDoGet_RetriesOnTemporaryNetError(t *testing.T) {
+	// Real server that will handle successful requests
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"status":"ok"}`))
+	}))
+	defer server.Close()
+
+	// Mock transport: fail twice with ECONNREFUSED, then succeed
+	mt := &mockTransport{
+		failCount:  2,
+		failErr:    &net.OpError{Op: "dial", Net: "tcp", Err: syscall.ECONNREFUSED},
+		realServer: server,
+	}
+
+	client := NewClient("http://fake-host/", "test-token")
+	client.SetHTTPClient(&http.Client{Transport: mt})
+	client.RetryBackoff = []time.Duration{1 * time.Millisecond, 1 * time.Millisecond}
+
+	body, err := client.doGet(context.Background(), "http://fake-host/test")
+	if err != nil {
+		t.Fatalf("expected success after retries, got error: %v", err)
+	}
+	if string(body) != `{"status":"ok"}` {
+		t.Errorf("body = %q, want %q", string(body), `{"status":"ok"}`)
+	}
+
+	// Should have made exactly 3 attempts: 2 failures + 1 success
+	if got := mt.attemptsMade.Load(); got != 3 {
+		t.Errorf("attempts = %d, want 3 (2 failures + 1 success)", got)
+	}
+}
+
+func TestIsTemporaryNetError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{"nil error", nil, false},
+		{"plain error", fmt.Errorf("some error"), false},
+		// OpError with retriable syscall errors
+		{"OpError ECONNREFUSED", &net.OpError{Op: "dial", Err: syscall.ECONNREFUSED}, true},
+		{"OpError ECONNRESET", &net.OpError{Op: "read", Err: syscall.ECONNRESET}, true},
+		{"OpError ENETUNREACH", &net.OpError{Op: "dial", Err: syscall.ENETUNREACH}, true},
+		{"OpError EHOSTUNREACH", &net.OpError{Op: "dial", Err: syscall.EHOSTUNREACH}, true},
+		{"OpError ETIMEDOUT", &net.OpError{Op: "dial", Err: syscall.ETIMEDOUT}, true},
+		// OpError with permanent syscall errors — should NOT retry
+		{"OpError EACCES", &net.OpError{Op: "dial", Err: syscall.EACCES}, false},
+		{"OpError EPERM", &net.OpError{Op: "dial", Err: syscall.EPERM}, false},
+		// OpError with unknown inner error — conservative retry
+		{"OpError unknown inner", &net.OpError{Op: "dial", Err: fmt.Errorf("unknown")}, true},
+		// DNS errors
+		{"DNS timeout", &net.DNSError{IsTimeout: true}, true},
+		{"DNS no such host", &net.DNSError{IsTimeout: false, Name: "bad.host"}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := isTemporaryNetError(tt.err)
+			if got != tt.want {
+				t.Errorf("isTemporaryNetError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestIsRetriableSyscallError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{"nil", nil, false},
+		{"ECONNREFUSED", syscall.ECONNREFUSED, true},
+		{"ECONNRESET", syscall.ECONNRESET, true},
+		{"ENETUNREACH", syscall.ENETUNREACH, true},
+		{"EHOSTUNREACH", syscall.EHOSTUNREACH, true},
+		{"ETIMEDOUT", syscall.ETIMEDOUT, true},
+		{"EACCES (permanent)", syscall.EACCES, false},
+		{"EPERM (permanent)", syscall.EPERM, false},
+		{"ENOENT (permanent)", syscall.ENOENT, false},
+		{"unknown error", fmt.Errorf("something"), true}, // conservative retry
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := isRetriableSyscallError(tt.err)
+			if got != tt.want {
+				t.Errorf("isRetriableSyscallError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestRedactURL(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{
+			name:  "no query params",
+			input: "https://gitea.example.com/api/v1/repos/owner/repo/pulls/1",
+			want:  "https://gitea.example.com/api/v1/repos/owner/repo/pulls/1",
+		},
+		{
+			name:  "with query params - redacts",
+			input: "https://gitea.example.com/api/v1/repos/owner/repo/raw/file?ref=main",
+			want:  "https://gitea.example.com/api/v1/repos/owner/repo/raw/file?[redacted]",
+		},
+		{
+			name:  "multiple query params",
+			input: "https://example.com/path?token=secret&page=1",
+			want:  "https://example.com/path?[redacted]",
+		},
+		{
+			name:  "invalid URL",
+			input: "://invalid",
+			want:  "[invalid URL]",
+		},
+		{
+			name:  "empty string",
+			input: "",
+			want:  "",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := redactURL(tt.input)
+			if got != tt.want {
+				t.Errorf("redactURL(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestSanitizeErrorForLog(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want string
+	}{
+		{
+			name: "nil error",
+			err:  nil,
+			want: "<nil>",
+		},
+		{
+			name: "APIError omits body",
+			err:  &APIError{StatusCode: 500, Body: "internal error: database connection failed"},
+			want: "HTTP 500",
+		},
+		{
+			name: "APIError with large body still only shows status",
+			err:  &APIError{StatusCode: 502, Body: strings.Repeat("x", 1000)},
+			want: "HTTP 502",
+		},
+		{
+			name: "non-API error preserved",
+			err:  fmt.Errorf("connection refused"),
+			want: "connection refused",
+		},
+		{
+			name: "wrapped APIError",
+			err:  fmt.Errorf("request failed: %w", &APIError{StatusCode: 503, Body: "service unavailable"}),
+			want: "HTTP 503",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := sanitizeErrorForLog(tt.err)
+			if got != tt.want {
+				t.Errorf("sanitizeErrorForLog() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
@@ -0,0 +1,27 @@
+//go:build phase2
+
+package vcs_test
+
+import (
+	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+// Compile-time assertion: documents the gap between gitea.Client and vcs.Client.
+// Guarded by the "phase2" build tag — enable once the Gitea adapter bridges these gaps:
+//
+//  1. PostReview signature mismatch:
+//     gitea.Client:  PostReview(ctx, owner, repo, number, event, body string, comments []gitea.ReviewComment)
+//     vcs.Reviewer:  PostReview(ctx, owner, repo, number, req vcs.ReviewRequest)
+//
+//  2. GetFileContent signature mismatch:
+//     gitea.Client:  GetFileContent(ctx, owner, repo, filepath string)  [no ref; uses default branch]
+//     vcs.FileReader: GetFileContent(ctx, owner, repo, path, ref string)
+//     (gitea.Client has GetFileContentRef for the ref variant)
+//
+//  3. ReviewComment type mismatch:
+//     gitea.ReviewComment uses NewPosition int64 (Gitea line-number convention)
+//     vcs.ReviewComment uses Position int (GitHub diff-position convention)
+//
+// The Gitea adapter (Phase 2) will wrap gitea.Client to bridge these gaps.
+var _ vcs.Client = (*gitea.Client)(nil)
@@ -0,0 +1,40 @@
+// Package vcs defines the shared VCS client interface and supporting types.
+// Platform adapters (gitea, github) implement these interfaces so the core
+// review logic can work with any VCS platform without platform-specific code.
+package vcs
+
+import "context"
+
+// PRReader can fetch pull request metadata, diffs, and changed files.
+type PRReader interface {
+	GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error)
+	GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
+	GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]ChangedFile, error)
+}
+
+// FileReader can fetch file contents and list directory entries.
+type FileReader interface {
+	GetFileContent(ctx context.Context, owner, repo, path, ref string) (string, error)
+	ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error)
+}
+
+// Reviewer can post, list, and delete pull request reviews.
+type Reviewer interface {
+	PostReview(ctx context.Context, owner, repo string, number int, req ReviewRequest) (*Review, error)
+	ListReviews(ctx context.Context, owner, repo string, number int) ([]Review, error)
+	DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
+}
+
+// Identity can report who the authenticated user is.
+type Identity interface {
+	GetAuthenticatedUser(ctx context.Context) (string, error)
+}
+
+// Client is the full VCS interface: PR reads, file reads, review management, and identity.
+// Platform adapters (gitea, github) implement this interface.
+type Client interface {
+	PRReader
+	FileReader
+	Reviewer
+	Identity
+}
@@ -0,0 +1,82 @@
+package vcs
+
+// ReviewEvent is the event type for a pull request review action.
+// Adapters must translate these action constants to/from platform-native values.
+// For example, Gitea uses "APPROVED" as both action and state, while GitHub
+// uses "APPROVE" for the action and returns "approved" as the state.
+type ReviewEvent string
+
+const (
+	// ReviewEventApprove approves the pull request.
+	ReviewEventApprove ReviewEvent = "APPROVE"
+	// ReviewEventRequestChanges requests changes to the pull request.
+	ReviewEventRequestChanges ReviewEvent = "REQUEST_CHANGES"
+	// ReviewEventComment posts a review comment without approval or rejection.
+	ReviewEventComment ReviewEvent = "COMMENT"
+)
+
+// HeadRef identifies the source branch and latest commit of a pull request.
+type HeadRef struct {
+	SHA string `json:"sha"`
+	Ref string `json:"ref"`
+}
+
+// UserInfo identifies a user by login name.
+type UserInfo struct {
+	Login string `json:"login"`
+}
+
+// PullRequest holds relevant PR metadata.
+type PullRequest struct {
+	Title string  `json:"title"`
+	Body  string  `json:"body"`
+	Head  HeadRef `json:"head"`
+}
+
+// ChangedFile represents a file modified in a PR.
+type ChangedFile struct {
+	Filename string `json:"filename"`
+	Status   string `json:"status"`
+}
+
+// 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"
+}
+
+// Review represents a pull request review.
+type Review struct {
+	ID       int64    `json:"id"`
+	Body     string   `json:"body"`
+	User     UserInfo `json:"user"`
+	State    string   `json:"state"`
+	Stale    bool     `json:"stale"`
+	CommitID string   `json:"commit_id"`
+}
+
+// ReviewComment represents an inline comment in a review.
+// All adapters use GitHub diff-position convention:
+//   - Position is a 1-indexed offset from the @@ hunk line in the unified diff.
+//   - CommitID identifies the commit the comment is anchored to.
+//     It is optional; omit (empty string) for review-level comments that are
+//     not attached to a specific commit.
+//
+// Adapters are responsible for translating to/from platform-native formats
+// (e.g. Gitea uses line numbers; GitHub uses diff positions natively).
+type ReviewComment struct {
+	Path     string `json:"path"`
+	Position int    `json:"position"` // diff-position: 1-indexed offset from @@ hunk line
+	CommitID string `json:"commit_id"`
+	Body     string `json:"body"`
+}
+
+// ReviewRequest is the payload for posting a review.
+type ReviewRequest struct {
+	// Body is the top-level review comment.
+	Body string `json:"body"`
+	// Event is the review action (approve, request changes, or comment).
+	Event    ReviewEvent     `json:"event"`
+	Comments []ReviewComment `json:"comments,omitempty"`
+}