README.md

@@ -296,6 +296,40 @@ review-bot \
   --conventions-file CONVENTIONS.md
 ```
 
+## Subcommands
+
+### `validate-docmap`
+
+Verifies that a `doc-map.yml` is consistent before running a review. Two checks:
+
+1. **Coverage**: every changed file is matched by at least one `paths:` glob.
+2. **Stale docs**: every `docs:` entry exists on disk under `--repo-root`.
+
+```bash
+# Typical CI usage — pipe git diff into the command
+git diff --name-only origin/main HEAD | \
+  review-bot validate-docmap \
+    --docmap .review-bot/doc-map.yml \
+    --repo-root .
+```
+
+| Flag | Required | Default | Description |
+|------|----------|---------|-------------|
+| `--docmap` | Yes | — | Path to doc-map YAML file |
+| `--repo-root` | No | `.` (cwd) | Root for resolving `docs:` paths |
+
+Exit codes: `0`=clean, `1`=failures found, `2`=usage/parse error.
+
+### `validate-url`
+
+Resolves a URL and verifies all IPs are publicly routable (used in CI to prevent SSRF).
+
+```bash
+review-bot validate-url https://gitea.example.com
+```
+
+Exit codes: `0`=safe, `1`=blocked/private IP, `2`=error.
+
 ## Environment Variables
 
 All flags have environment variable equivalents:

TODO.md

@@ -1,42 +0,0 @@
-## Dev Loop Status: 2026-05-15 04:35 UTC
-
-**Repository:** review-bot (rodin/review-bot on Gitea)  
-**Status:** ✅ OPTIMAL
-
-### Health Check
-
-- **Working tree:** clean
-- **Branch:** main (up to date with origin)
-- **Build:** ✅ passes (`go build ./cmd/review-bot`)
-- **Tests:** ✅ ALL PASS (6/6 packages)
-- **Vet:** ✅ clean
-- **Open issues:** 0
-- **Open PRs:** 0
-
-### Recent Changes
-
-- ✅ Merged PR #140: test coverage improvements (44.6% → 49.3%)
-- ✅ PR #137 (doc-map feature) merged successfully with all reviews approved
-
-### Coverage
-
-| Package | Coverage |
-|---------|----------|
-| cmd/review-bot | 49.3% ↑ |
-| gitea | 85.2% |
-| github | 86.3% |
-| review | 92.0% |
-
-### Status Summary
-
-All recent feature work (doc-map, coverage improvements) successfully integrated. Repository is stable and ready for next development cycle.
-
-### Next Priority
-
-- Continue increasing cmd/review-bot coverage (target: ≥60%)
-- Monitor prod logs for edge cases
-- VCS integration stable; GitHub + Gitea paths clear
-
----
-
-_Dev-loop cycle complete at 04:35 UTC._

cmd/review-bot/main.go

@@ -64,6 +64,8 @@ func main() {
 		switch os.Args[1] {
 		case "validate-url":
 			os.Exit(runValidateURL(os.Args[2:]))
+		case "validate-docmap":
+			os.Exit(runValidateDocmap(os.Args[2:]))
 		}
 	}
 

cmd/review-bot/validatedocmap.go

@@ -0,0 +1,263 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gitea.weiker.me/rodin/review-bot/review"
+)
+
+// maxDocmapBytes is the maximum size of the doc-map YAML file that will be
+// read. Files larger than this are rejected before reading to prevent memory
+// exhaustion from an oversized PR-controlled file.
+const maxDocmapBytes int64 = 10 * 1024 * 1024 // 10 MB
+
+// validateDocmapPath checks that localPath is safe to read as the doc-map
+// file. It enforces three invariants before the file is opened:
+//
+//  1. The path resolves to a regular file within resolvedRoot (path
+//     confinement): prevents a PR-controlled --docmap from reading arbitrary
+//     host files via absolute paths or ".." traversal.
+//  2. The path is not a symlink: prevents denial-of-service via /dev/zero or
+//     information disclosure via symlinks that point outside the workspace.
+//  3. The file does not exceed maxDocmapBytes: prevents memory exhaustion
+//     from an oversized but legitimately committed doc-map file.
+//
+// resolvedRoot must already be an absolute, symlink-free path (obtained from
+// filepath.Abs + filepath.EvalSymlinks).
+func validateDocmapPath(localPath, resolvedRoot string) error {
+	// Resolve the docmap path to an absolute path.
+	absPath, err := filepath.Abs(localPath)
+	if err != nil {
+		return fmt.Errorf("cannot resolve path: %w", err)
+	}
+
+	// Lstat: do NOT follow symlinks. We want to inspect the entry itself.
+	fi, err := os.Lstat(absPath)
+	if err != nil {
+		return fmt.Errorf("cannot stat file: %w", err)
+	}
+
+	// Reject symlinks outright — a symlink can point to /dev/zero or arbitrary
+	// host paths, bypassing both the confinement check and the size check.
+	if fi.Mode()&os.ModeSymlink != 0 {
+		return fmt.Errorf("symlinks are not allowed")
+	}
+
+	// Confine to resolvedRoot: the cleaned absolute path must be a descendant
+	// of the repo root. This catches paths that escaped via "..", absolute
+	// paths that happen to be outside the root, etc.
+	rel, err := filepath.Rel(resolvedRoot, absPath)
+	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(os.PathSeparator)) {
+		return fmt.Errorf("path must be within --repo-root")
+	}
+
+	// Enforce size cap before reading to prevent memory exhaustion.
+	if fi.Size() > maxDocmapBytes {
+		return fmt.Errorf("file size %d bytes exceeds %d-byte limit", fi.Size(), maxDocmapBytes)
+	}
+
+	return nil
+}
+
+// runValidateDocmap implements the `review-bot validate-docmap` subcommand.
+//
+// It reads changed file paths from stdin (one per line, as produced by
+// `git diff --name-only`), parses a doc-map YAML file, and performs two checks:
+//
+//  1. Coverage check: every changed file must be matched by at least one
+//     paths: glob in the docmap. Fails if any file is uncovered.
+//
+//  2. Stale-docs check: every docs: entry in the docmap must exist on disk
+//     (relative to --repo-root). Fails if any path is missing.
+//
+// Both checks always run — all failures are reported before exiting.
+//
+// Exit codes:
+//
+//	0 — clean (all files covered, all docs exist)
+//	1 — one or more coverage or stale-doc failures
+//	2 — usage error, missing flag, or YAML parse error
+func runValidateDocmap(args []string) int {
+	fs := flag.NewFlagSet("validate-docmap", flag.ContinueOnError)
+	fs.SetOutput(errWriter)
+
+	docmapFlag := fs.String("docmap", "", "Path to doc-map YAML file (required)")
+	repoRootFlag := fs.String("repo-root", ".", "Repo root for resolving docs: paths (default: cwd)")
+
+	if err := fs.Parse(args); err != nil {
+		// flag.ContinueOnError already wrote the error to errWriter.
+		return 2
+	}
+
+	if *docmapFlag == "" {
+		fmt.Fprintln(errWriter, "Error: --docmap is required")
+		fmt.Fprintln(errWriter, "")
+		fmt.Fprintln(errWriter, "usage: review-bot validate-docmap --docmap <path> [--repo-root <dir>]")
+		fmt.Fprintln(errWriter, "  Changed files are read from stdin, one per line.")
+		fmt.Fprintln(errWriter, "  Example: git diff --name-only origin/main HEAD | review-bot validate-docmap --docmap .review-bot/doc-map.yml")
+		return 2
+	}
+
+	// Resolve repoRoot first — the docmap path is validated against it below.
+	// Use an absolute, symlink-free path so a symlinked --repo-root cannot
+	// bypass the escape guard in validateDocmapPath or checkStaleDocs.
+	absRoot, err := filepath.Abs(*repoRootFlag)
+	if err != nil {
+		fmt.Fprintf(errWriter, "Error: failed to resolve --repo-root %q: %v\n", *repoRootFlag, err)
+		return 2
+	}
+	resolvedRoot, err := filepath.EvalSymlinks(absRoot)
+	if err != nil {
+		if os.IsNotExist(err) {
+			fmt.Fprintf(errWriter, "Error: --repo-root %q does not exist\n", *repoRootFlag)
+		} else {
+			fmt.Fprintf(errWriter, "Error: failed to resolve --repo-root %q: %v\n", *repoRootFlag, err)
+		}
+		return 2
+	}
+
+	// Harden the docmap file path before reading it. The --docmap flag value
+	// may reference a PR-controlled file (e.g. .review-bot/doc-map.yml).
+	// Validate that it:
+	//   1. Resolves within resolvedRoot (prevent reading arbitrary host files).
+	//   2. Is not a symlink (prevent /dev/zero or symlink-based host probing).
+	//   3. Does not exceed maxDocmapBytes (prevent memory exhaustion from an
+	//      oversized committed file).
+	if err := validateDocmapPath(*docmapFlag, resolvedRoot); err != nil {
+		fmt.Fprintf(errWriter, "Error: --docmap %q is invalid: %v\n", *docmapFlag, err)
+		return 2
+	}
+
+	// Parse docmap YAML.
+	cfg, err := review.ParseDocMapConfig(*docmapFlag)
+	if err != nil {
+		fmt.Fprintf(errWriter, "Error: failed to parse docmap %q: %v\n", *docmapFlag, err)
+		return 2
+	}
+
+	// Read changed files from stdin.
+	changedFiles, err := readLines(os.Stdin)
+	if err != nil {
+		fmt.Fprintf(errWriter, "Error: failed to read stdin: %v\n", err)
+		return 2
+	}
+
+	failed := false
+
+	// --- Check 1: Coverage ---
+	// Note: an empty docmap (no mappings) means every changed file is
+	// uncovered — there are no patterns to match against. This is intentional:
+	// if you declare a doc-map, every changed file must be accounted for.
+	// On empty stdin the check is vacuously true (no files to cover).
+	var uncovered []string
+	for _, f := range changedFiles {
+		// Normalize Windows-style backslashes to forward slashes so that
+		// changed-file paths from git on Windows match doc-map globs.
+		f = strings.ReplaceAll(f, "\\", "/")
+		if !review.FileCoveredByDocMap(cfg, f) {
+			uncovered = append(uncovered, f)
+		}
+	}
+	if len(uncovered) > 0 {
+		failed = true
+		fmt.Fprintln(errWriter, "ERROR: changed files with no docmap coverage:")
+		for _, f := range uncovered {
+			fmt.Fprintf(errWriter, "  %s\n", f)
+		}
+	}
+
+	// --- Check 2: Stale docs ---
+	// checkStaleDocs validates each path before touching the filesystem; see
+	// its documentation for the path-traversal hardening applied.
+	staleDocs := checkStaleDocs(cfg, resolvedRoot)
+	if len(staleDocs) > 0 {
+		failed = true
+		fmt.Fprintln(errWriter, "ERROR: stale docmap docs: entries (paths do not exist):")
+		for _, d := range staleDocs {
+			fmt.Fprintf(errWriter, "  %s\n", d)
+		}
+	}
+
+	if failed {
+		return 1
+	}
+
+	fmt.Fprintln(outWriter, "OK: docmap is valid")
+	return 0
+}
+
+// checkStaleDocs returns deduplicated docs: entries that do not exist under
+// repoRoot.
+//
+// Path-traversal hardening: each docPath is validated with
+// review.ValidateDocPath (rejects absolute paths and ".." segments) and then
+// confined to repoRoot via filepath.Clean + filepath.Rel before os.Lstat is
+// called. Symlinks are treated as stale — a CI tool running against
+// PR-controlled content must not follow symlinks that could probe arbitrary
+// host paths. Paths that fail any check are treated as invalid (reported as
+// stale) without following any symlinks.
+func checkStaleDocs(cfg *review.DocMapConfig, repoRoot string) []string {
+	seen := make(map[string]struct{})
+	var stale []string
+
+	for _, mapping := range cfg.Mappings {
+		for _, docPath := range mapping.Docs {
+			if docPath == "" {
+				continue
+			}
+			if _, ok := seen[docPath]; ok {
+				continue
+			}
+			seen[docPath] = struct{}{}
+
+			// Guard 1: reject absolute paths and ".." segments sourced from
+			// PR-controlled YAML before joining with repoRoot.
+			if err := review.ValidateDocPath(docPath); err != nil {
+				stale = append(stale, docPath)
+				continue
+			}
+
+			// Guard 2: verify the cleaned joined path does not escape repoRoot.
+			// filepath.Clean resolves any remaining ".." after the join; the
+			// filepath.Rel check confirms the path is still under repoRoot.
+			fullPath := filepath.Clean(filepath.Join(repoRoot, filepath.FromSlash(docPath)))
+			rel, err := filepath.Rel(repoRoot, fullPath)
+			if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(os.PathSeparator)) {
+				stale = append(stale, docPath)
+				continue
+			}
+
+			// Use Lstat (not Stat) so symlinks are never followed. A symlink
+			// under repoRoot could point anywhere on the host, allowing a
+			// malicious PR to probe file existence. Treat symlinks as stale.
+			fi, err := os.Lstat(fullPath)
+			if err != nil {
+				stale = append(stale, docPath)
+				continue
+			}
+			if fi.Mode()&os.ModeSymlink != 0 {
+				stale = append(stale, docPath)
+			}
+		}
+	}
+	return stale
+}
+
+// readLines reads all non-empty trimmed lines from r.
+func readLines(r io.Reader) ([]string, error) {
+	scanner := bufio.NewScanner(r)
+	var lines []string
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line != "" {
+			lines = append(lines, line)
+		}
+	}
+	return lines, scanner.Err()
+}

cmd/review-bot/validatedocmap_test.go

@@ -0,0 +1,552 @@
+package main
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// makeDocmapYAML writes a YAML string to a temp file and returns its path.
+// The file is created in t.TempDir() — use makeDocmapInDir when the docmap
+// must be located inside a specific repo-root directory.
+func makeDocmapYAML(t *testing.T, content string) string {
+	t.Helper()
+	f, err := os.CreateTemp(t.TempDir(), "doc-map-*.yml")
+	if err != nil {
+		t.Fatalf("CreateTemp: %v", err)
+	}
+	defer f.Close()
+	if _, err := f.WriteString(content); err != nil {
+		t.Fatalf("WriteString: %v", err)
+	}
+	return f.Name()
+}
+
+// makeDocmapInDir writes a YAML string to a file inside dir and returns the
+// file path. Use this instead of makeDocmapYAML when also passing --repo-root,
+// because validateDocmapPath requires the docmap to be within the repo root.
+func makeDocmapInDir(t *testing.T, dir, content string) string {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Join(dir, ".review-bot"), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	path := filepath.Join(dir, ".review-bot", "doc-map.yml")
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+	return path
+}
+
+// makeDocFile creates a file (and any parent dirs) at the given path relative to dir.
+func makeDocFile(t *testing.T, dir, rel string) {
+	t.Helper()
+	full := filepath.Join(dir, rel)
+	if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(full, []byte("# doc\n"), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+}
+
+// captureOutput redirects outWriter/errWriter to buffers for the duration of f.
+func captureOutput(f func()) (stdout, stderr string) {
+	var outBuf, errBuf bytes.Buffer
+	origOut, origErr := outWriter, errWriter
+	outWriter = &outBuf
+	errWriter = &errBuf
+	defer func() {
+		outWriter = origOut
+		errWriter = origErr
+	}()
+	f()
+	return outBuf.String(), errBuf.String()
+}
+
+func TestRunValidateDocmap_Clean(t *testing.T) {
+	dir := t.TempDir()
+	makeDocFile(t, dir, "docs/foo.md")
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	// A covered file with all docs existing → clean.
+	code, stdout, _ := stdinValidateDocmap(t,
+		"lib/foo/bar.ex\n",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 0 {
+		t.Errorf("expected exit 0 for clean, got %d", code)
+	}
+	if !strings.Contains(stdout, "OK") {
+		t.Errorf("expected 'OK' in stdout, got %q", stdout)
+	}
+}
+
+func TestRunValidateDocmap_MissingDocmapFlag(t *testing.T) {
+	var code int
+	_, stderr := captureOutput(func() {
+		code = runValidateDocmap([]string{})
+	})
+	if code != 2 {
+		t.Errorf("expected exit 2 for missing --docmap, got %d", code)
+	}
+	if !strings.Contains(stderr, "--docmap") {
+		t.Errorf("expected --docmap in stderr, got %q", stderr)
+	}
+}
+
+func TestRunValidateDocmap_BadYAML(t *testing.T) {
+	dir := t.TempDir()
+	docmap := makeDocmapInDir(t, dir, "mappings: [{{invalid")
+	var code int
+	_, stderr := captureOutput(func() {
+		code = runValidateDocmap([]string{"--docmap", docmap, "--repo-root", dir})
+	})
+	if code != 2 {
+		t.Errorf("expected exit 2 for bad YAML, got %d", code)
+	}
+	if !strings.Contains(stderr, "failed to parse") {
+		t.Errorf("expected parse error in stderr, got %q", stderr)
+	}
+}
+
+func TestRunValidateDocmap_StaleDocs(t *testing.T) {
+	dir := t.TempDir()
+	// docs/foo.md does NOT exist on disk.
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	var code int
+	_, stderr := captureOutput(func() {
+		code = runValidateDocmap([]string{
+			"--docmap", docmap,
+			"--repo-root", dir,
+		})
+	})
+	if code != 1 {
+		t.Errorf("expected exit 1 for stale docs, got %d", code)
+	}
+	if !strings.Contains(stderr, "docs/foo.md") {
+		t.Errorf("expected stale path in stderr, got %q", stderr)
+	}
+	if !strings.Contains(stderr, "stale docmap") {
+		t.Errorf("expected 'stale docmap' in stderr, got %q", stderr)
+	}
+}
+
+// stdinValidateDocmap runs runValidateDocmap with a synthetic stdin.
+//
+// Implementation note: we write stdinContent to a temp file and point
+// os.Stdin at it. The defer f.Close() fires after stdinValidateDocmap
+// returns, which is after runValidateDocmap has finished reading stdin
+// synchronously — so the file is not closed while still in use.
+// Tests must not call t.Parallel() while sharing the global os.Stdin.
+func stdinValidateDocmap(t *testing.T, stdinContent string, args []string) (code int, stdout, stderr string) {
+	t.Helper()
+	// Write stdin content to a temp file and redirect os.Stdin.
+	f, err := os.CreateTemp(t.TempDir(), "stdin-*")
+	if err != nil {
+		t.Fatalf("CreateTemp for stdin: %v", err)
+	}
+	defer f.Close()
+	if _, err := f.WriteString(stdinContent); err != nil {
+		t.Fatalf("WriteString for stdin: %v", err)
+	}
+	if _, err := f.Seek(0, 0); err != nil {
+		t.Fatalf("Seek for stdin: %v", err)
+	}
+
+	origStdin := os.Stdin
+	os.Stdin = f
+	defer func() { os.Stdin = origStdin }()
+
+	stdout, stderr = captureOutput(func() {
+		code = runValidateDocmap(args)
+	})
+	return
+}
+
+func TestRunValidateDocmap_UncoveredFile(t *testing.T) {
+	dir := t.TempDir()
+	makeDocFile(t, dir, "docs/foo.md")
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"lib/bar/uncovered.ex\n",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 1 {
+		t.Errorf("expected exit 1 for uncovered file, got %d", code)
+	}
+	if !strings.Contains(stderr, "lib/bar/uncovered.ex") {
+		t.Errorf("expected uncovered file in stderr, got %q", stderr)
+	}
+	if !strings.Contains(stderr, "no docmap coverage") {
+		t.Errorf("expected 'no docmap coverage' in stderr, got %q", stderr)
+	}
+}
+
+func TestRunValidateDocmap_BothFailures(t *testing.T) {
+	dir := t.TempDir()
+	// docs/foo.md intentionally missing
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"lib/bar/uncovered.ex\n",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 1 {
+		t.Errorf("expected exit 1 for both failures, got %d", code)
+	}
+	if !strings.Contains(stderr, "no docmap coverage") {
+		t.Errorf("expected coverage error in stderr, got %q", stderr)
+	}
+	if !strings.Contains(stderr, "stale docmap") {
+		t.Errorf("expected stale-docs error in stderr, got %q", stderr)
+	}
+}
+
+func TestRunValidateDocmap_EmptyStdin(t *testing.T) {
+	dir := t.TempDir()
+	makeDocFile(t, dir, "docs/foo.md")
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	code, stdout, _ := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 0 {
+		t.Errorf("expected exit 0 for empty stdin, got %d", code)
+	}
+	if !strings.Contains(stdout, "OK") {
+		t.Errorf("expected 'OK' in stdout, got %q", stdout)
+	}
+}
+
+func TestRunValidateDocmap_BlankLinesSkipped(t *testing.T) {
+	dir := t.TempDir()
+	makeDocFile(t, dir, "docs/foo.md")
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/foo.md
+`)
+
+	// stdin with only blank lines → effectively empty, should be clean
+	code, stdout, _ := stdinValidateDocmap(t,
+		"\n  \n\n",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 0 {
+		t.Errorf("expected exit 0 for blank-only stdin, got %d", code)
+	}
+	if !strings.Contains(stdout, "OK") {
+		t.Errorf("expected 'OK' in stdout for blank-only stdin, got %q", stdout)
+	}
+}
+
+func TestRunValidateDocmap_DuplicateDocsDeduped(t *testing.T) {
+	dir := t.TempDir()
+	// docs/shared.md intentionally missing — but it appears in TWO mappings.
+	// Should appear only once in stale list.
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/foo/**"
+    docs:
+      - docs/shared.md
+  - paths:
+      - "lib/bar/**"
+    docs:
+      - docs/shared.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 1 {
+		t.Errorf("expected exit 1 for stale doc, got %d", code)
+	}
+	count := strings.Count(stderr, "docs/shared.md")
+	if count != 1 {
+		t.Errorf("expected docs/shared.md to appear exactly once in stderr (deduplicated), got %d occurrences: %q", count, stderr)
+	}
+}
+
+// TestCheckStaleDocs_PathTraversal verifies that checkStaleDocs rejects
+// traversal and absolute paths without touching the host filesystem.
+func TestCheckStaleDocs_PathTraversal(t *testing.T) {
+	dir := t.TempDir()
+
+	// Baseline: a valid doc that exists.
+	makeDocFile(t, dir, "docs/valid.md")
+
+	tests := []struct {
+		name      string
+		docPath   string
+		wantStale bool
+	}{
+		{"dot-dot traversal", "../../etc/passwd", true},
+		{"dot-dot single", "../outside", true},
+		{"absolute path", "/etc/passwd", true},
+		{"valid present path", "docs/valid.md", false},
+		{"valid missing path", "docs/missing.md", true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - `+tc.docPath+`
+`)
+			code, _, stderr := stdinValidateDocmap(t,
+				"",
+				[]string{"--docmap", docmap, "--repo-root", dir},
+			)
+
+			if tc.wantStale {
+				if code != 1 {
+					t.Errorf("path %q: expected exit 1 (stale/invalid), got %d; stderr: %q", tc.docPath, code, stderr)
+				}
+			} else {
+				if code != 0 {
+					t.Errorf("path %q: expected exit 0 (valid), got %d; stderr: %q", tc.docPath, code, stderr)
+				}
+			}
+		})
+	}
+}
+
+// TestCheckStaleDocs_SymlinkOutside verifies that a symlink under repoRoot
+// pointing outside the repo is treated as stale (not followed).
+func TestCheckStaleDocs_SymlinkOutside(t *testing.T) {
+	dir := t.TempDir()
+
+	// Create a symlink inside repoRoot pointing to a file outside the repo.
+	// We point at /etc/hostname (exists on Linux CI) but the test does not
+	// depend on that file existing — Lstat must reject the symlink itself.
+	linkPath := filepath.Join(dir, "docs", "secret.md")
+	if err := os.MkdirAll(filepath.Dir(linkPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.Symlink("/etc/hostname", linkPath); err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - docs/secret.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 1 {
+		t.Errorf("expected exit 1 for symlink doc, got %d; stderr: %q", code, stderr)
+	}
+	if !strings.Contains(stderr, "docs/secret.md") {
+		t.Errorf("expected stale path in stderr, got %q", stderr)
+	}
+}
+
+// TestCheckStaleDocs_SymlinkInsideRepo verifies that a symlink pointing to
+// another file *within* the repo is also treated as stale. We refuse all
+// symlinks regardless of target to keep the check simple and safe.
+func TestCheckStaleDocs_SymlinkInsideRepo(t *testing.T) {
+	dir := t.TempDir()
+
+	// Real doc file.
+	makeDocFile(t, dir, "docs/real.md")
+
+	// Symlink inside repo pointing at the real file.
+	linkPath := filepath.Join(dir, "docs", "link.md")
+	if err := os.Symlink(filepath.Join(dir, "docs", "real.md"), linkPath); err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	docmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - docs/link.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", docmap, "--repo-root", dir},
+	)
+	if code != 1 {
+		t.Errorf("expected exit 1 for symlink doc (even intra-repo), got %d; stderr: %q", code, stderr)
+	}
+}
+
+// TestRunValidateDocmap_SymlinkRepoRoot verifies that a --repo-root that is
+// itself a symlink to a valid directory resolves correctly.
+func TestRunValidateDocmap_SymlinkRepoRoot(t *testing.T) {
+	realDir := t.TempDir()
+	makeDocFile(t, realDir, "docs/foo.md")
+
+	// Create a symlink pointing at realDir.
+	symlinkDir := filepath.Join(t.TempDir(), "link-root")
+	if err := os.Symlink(realDir, symlinkDir); err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	// Place the docmap inside realDir so it passes the confinement check.
+	// (symlinkDir resolves to realDir, so files inside realDir are also inside
+	// the resolved repo-root.)
+	docmap := makeDocmapInDir(t, realDir, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - docs/foo.md
+`)
+
+	// Using the symlinked repo-root: the real doc exists → should be clean.
+	code, stdout, stderr := stdinValidateDocmap(t,
+		"lib/foo.go\n",
+		[]string{"--docmap", docmap, "--repo-root", symlinkDir},
+	)
+	if code != 0 {
+		t.Errorf("expected exit 0 for symlinked repo-root with existing doc, got %d; stderr: %q", code, stderr)
+	}
+	if !strings.Contains(stdout, "OK") {
+		t.Errorf("expected 'OK' in stdout, got %q", stdout)
+	}
+}
+
+// TestValidateDocmapPath_Symlink verifies that --docmap pointing at a symlink
+// is rejected before the file is read (prevents /dev/zero DOS or arbitrary
+// host-file reads via PR-controlled symlinks).
+func TestValidateDocmapPath_Symlink(t *testing.T) {
+	dir := t.TempDir()
+
+	// Create a real docmap file to serve as the symlink target.
+	realDocmap := makeDocmapInDir(t, dir, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - docs/foo.md
+`)
+
+	// Create a symlink inside dir pointing to the real docmap.
+	symlinkPath := filepath.Join(dir, ".review-bot", "doc-map-link.yml")
+	if err := os.Symlink(realDocmap, symlinkPath); err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", symlinkPath, "--repo-root", dir},
+	)
+	if code != 2 {
+		t.Errorf("expected exit 2 for symlink docmap, got %d; stderr: %q", code, stderr)
+	}
+	if !strings.Contains(stderr, "symlink") && !strings.Contains(stderr, "invalid") {
+		t.Errorf("expected symlink rejection in stderr, got %q", stderr)
+	}
+}
+
+// TestValidateDocmapPath_OutsideRepoRoot verifies that --docmap pointing
+// outside --repo-root is rejected (prevents reading arbitrary host files).
+func TestValidateDocmapPath_OutsideRepoRoot(t *testing.T) {
+	repoDir := t.TempDir()
+
+	// Create a docmap in a separate temp dir (outside the repo root).
+	outside := makeDocmapYAML(t, `
+mappings:
+  - paths:
+      - "lib/**"
+    docs:
+      - docs/foo.md
+`)
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", outside, "--repo-root", repoDir},
+	)
+	if code != 2 {
+		t.Errorf("expected exit 2 for docmap outside repo-root, got %d; stderr: %q", code, stderr)
+	}
+	if !strings.Contains(stderr, "invalid") && !strings.Contains(stderr, "repo-root") {
+		t.Errorf("expected confinement rejection in stderr, got %q", stderr)
+	}
+}
+
+// TestValidateDocmapPath_SizeLimit verifies that --docmap files exceeding
+// maxDocmapBytes are rejected before reading (prevents memory exhaustion).
+func TestValidateDocmapPath_SizeLimit(t *testing.T) {
+	dir := t.TempDir()
+
+	// Write a file larger than maxDocmapBytes.
+	bigPath := filepath.Join(dir, ".review-bot", "big-doc-map.yml")
+	if err := os.MkdirAll(filepath.Dir(bigPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	// Exceed the limit by one byte.
+	bigContent := make([]byte, maxDocmapBytes+1)
+	if err := os.WriteFile(bigPath, bigContent, 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	code, _, stderr := stdinValidateDocmap(t,
+		"",
+		[]string{"--docmap", bigPath, "--repo-root", dir},
+	)
+	if code != 2 {
+		t.Errorf("expected exit 2 for oversized docmap, got %d; stderr: %q", code, stderr)
+	}
+	if !strings.Contains(stderr, "limit") && !strings.Contains(stderr, "size") && !strings.Contains(stderr, "invalid") {
+		t.Errorf("expected size limit error in stderr, got %q", stderr)
+	}
+}

review/docmap.go

@@ -66,6 +66,18 @@ func ParseDocMapConfig(localPath string) (*DocMapConfig, error) {
 	return &cfg, nil
 }
 
+// FileCoveredByDocMap reports whether at least one paths: glob in any mapping
+// of cfg matches the given file path. It is used by static validation tooling
+// (e.g. the validate-docmap subcommand) to check per-file docmap coverage.
+func FileCoveredByDocMap(cfg *DocMapConfig, file string) bool {
+	for _, mapping := range cfg.Mappings {
+		if mappingMatches(mapping.Paths, []string{file}) {
+			return true
+		}
+	}
+	return false
+}
+
 // MatchDocs returns deduplicated doc paths for the given changed file paths.
 // A mapping matches if any of its path globs matches any of the changed files.
 func MatchDocs(cfg *DocMapConfig, changedFiles []string) []string {
@@ -245,7 +257,7 @@ type docEntry struct {
 // If the path is a directory, all .md files under it are returned.
 // If it's a file, a single entry is returned.
 func loadDocEntries(ctx context.Context, fetcher DocFetcher, owner, repo, docPath string) ([]docEntry, error) {
-	if err := validateDocPath(docPath); err != nil {
+	if err := ValidateDocPath(docPath); err != nil {
 		return nil, fmt.Errorf("doc path %q rejected: %w", docPath, err)
 	}
 
@@ -298,11 +310,15 @@ func readFileBytes(path string) ([]byte, error) {
 	return os.ReadFile(path)
 }
 
-// validateDocPath rejects doc paths that could cause path traversal via the
-// VCS API (absolute paths, any ".." segment). Defense-in-depth: the VCS API
-// should already scope paths to the repo, but we validate locally to avoid
-// any quirk in backend path handling.
-func validateDocPath(p string) error {
+// ValidateDocPath rejects doc paths that could cause path traversal
+// (absolute paths, any ".." segment, backslashes). Defense-in-depth: callers
+// must also confine the joined path to the repo root via filepath.Rel before
+// any filesystem access. Backslashes are rejected explicitly to prevent
+// Windows platform edge cases.
+func ValidateDocPath(p string) error {
+	if strings.Contains(p, "\\") {
+		return fmt.Errorf("backslashes not allowed in doc paths")
+	}
 	if filepath.IsAbs(p) {
 		return fmt.Errorf("absolute paths not allowed")
 	}

review/docmap_test.go

@@ -384,7 +384,7 @@ func TestValidateDocPath(t *testing.T) {
 		"a/b/c",
 	}
 	for _, p := range valid {
-		if err := validateDocPath(p); err != nil {
+		if err := ValidateDocPath(p); err != nil {
 			t.Errorf("expected valid path %q to pass, got error: %v", p, err)
 		}
 	}
@@ -395,9 +395,13 @@ func TestValidateDocPath(t *testing.T) {
 		"docs/../../../etc/passwd",
 		"../sibling-repo/file.md",
 		"a/b/../c",
+		// Backslashes must be rejected (Finding #3 — Windows platform edge cases).
+		`docs\foo.md`,
+		`docs\..\secret`,
+		`\absolute`,
 	}
 	for _, p := range invalid {
-		if err := validateDocPath(p); err == nil {
+		if err := ValidateDocPath(p); err == nil {
 			t.Errorf("expected path %q to be rejected, but it was accepted", p)
 		}
 	}
@@ -420,6 +424,27 @@ func TestLoadMatchingDocs_PathTraversalRejected(t *testing.T) {
 	}
 }
 
+// TestValidateDocPath_Backslash verifies that backslash-bearing paths are
+// rejected to prevent Windows platform edge cases where a path separator
+// could be normalised differently by the host OS or VCS backend.
+func TestValidateDocPath_Backslash(t *testing.T) {
+	backslashPaths := []string{
+		`docs\foo.md`,
+		`docs\subdir\file.md`,
+		`\absolute`,
+	}
+	for _, p := range backslashPaths {
+		if err := ValidateDocPath(p); err == nil {
+			t.Errorf("expected backslash path %q to be rejected, but it was accepted", p)
+		}
+	}
+
+	// Sanity: forward-slash path must still be accepted.
+	if err := ValidateDocPath("docs/foo.md"); err != nil {
+		t.Errorf("expected forward-slash path to be accepted, got: %v", err)
+	}
+}
+
 // ============================================================
 // Helpers
 // ============================================================
@@ -436,3 +461,52 @@ func writeTempYAML(t *testing.T, content string) string {
 	}
 	return filepath.Clean(f.Name())
 }
+
+// ============================================================
+// FileCoveredByDocMap
+// ============================================================
+
+func TestFileCoveredByDocMap(t *testing.T) {
+	cfg := &DocMapConfig{
+		Mappings: []DocMapping{
+			{
+				Paths: []string{"lib/foo/**", "lib/bar/*.go"},
+				Docs:  []string{"docs/foo.md"},
+			},
+			{
+				Paths: []string{"cmd/**"},
+				Docs:  []string{"docs/cmd.md"},
+			},
+		},
+	}
+
+	cases := []struct {
+		file    string
+		covered bool
+	}{
+		{"lib/foo/baz.ex", true},
+		{"lib/foo/sub/deep.ex", true},
+		{"lib/bar/util.go", true},
+		{"lib/bar/sub/util.go", false}, // *.go only matches one level
+		{"cmd/main.go", true},
+		{"cmd/sub/main.go", true},
+		{"internal/secret.go", false},
+		{"", false},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.file, func(t *testing.T) {
+			got := FileCoveredByDocMap(cfg, tc.file)
+			if got != tc.covered {
+				t.Errorf("FileCoveredByDocMap(%q) = %v, want %v", tc.file, got, tc.covered)
+			}
+		})
+	}
+}
+
+func TestFileCoveredByDocMap_EmptyConfig(t *testing.T) {
+	cfg := &DocMapConfig{}
+	if FileCoveredByDocMap(cfg, "lib/foo/bar.go") {
+		t.Error("expected false for empty config, got true")
+	}
+}