fix(memory): add pre-commit guard to validate skill formatting (#1482)

Co-authored-by: Letta Code <noreply@letta.com>

src/agent/memoryGit.ts

@@ -165,6 +165,12 @@ PROTECTED_KEYS="read_only"
 ALL_KNOWN_KEYS="description limit read_only"
 errors=""
 
+# Skills must always be directories: skills/<name>/SKILL.md
+# Reject legacy flat skill files (both current and legacy repo layouts).
+for file in $(git diff --cached --name-only --diff-filter=ACMR | grep -E '^(memory/)?skills/[^/]+\\.md$' || true); do
+  errors="$errors\\n  $file: invalid skill path (skills must be folders). Use skills/<name>/SKILL.md"
+done
+
 # Helper: extract a frontmatter value from content
 get_fm_value() {
   local content="$1" key="$2"
@@ -174,7 +180,9 @@ get_fm_value() {
   echo "$content" | tail -n +2 | head -n $((closing_line - 1)) | grep "^$key:" | cut -d: -f2- | sed 's/^ *//;s/ *$//'
 }
 
-for file in $(git diff --cached --name-only --diff-filter=ACM | grep '^memory/.*\\.md$'); do
+# Match .md files under system/ or reference/ (with optional memory/ prefix).
+# Skip skill SKILL.md files — they use a different frontmatter format.
+for file in $(git diff --cached --name-only --diff-filter=ACM | grep -E '^(memory/)?(system|reference)/.*\\.md$'); do
   staged=$(git show ":$file")
 
   # Frontmatter is required

src/tests/agent/memoryGit.precommit.test.ts

@@ -290,6 +290,65 @@ describe("pre-commit hook: read_only protection", () => {
   });
 });
 
+describe("pre-commit hook: skill path guard", () => {
+  test("rejects legacy flat skill file in nested memory layout", () => {
+    writeAndStage(
+      "memory/skills/slack-search.md",
+      `${VALID_FM}Legacy flat skill file.\n`,
+    );
+    const result = tryCommit();
+    expect(result.success).toBe(false);
+    expect(result.output).toContain("Use skills/<name>/SKILL.md");
+  });
+
+  test("rejects legacy flat skill file in top-level layout", () => {
+    writeAndStage("skills/slack-search.md", "Legacy flat skill file.\n");
+    const result = tryCommit();
+    expect(result.success).toBe(false);
+    expect(result.output).toContain("Use skills/<name>/SKILL.md");
+  });
+
+  test("allows canonical directory-based skill path", () => {
+    writeAndStage("skills/slack-search/SKILL.md", "# Slack Search\n");
+    const result = tryCommit();
+    expect(result.success).toBe(true);
+  });
+});
+
+describe("pre-commit hook: top-level layout (no memory/ prefix)", () => {
+  test("validates frontmatter for system files without memory/ prefix", () => {
+    writeAndStage(
+      "system/human.md",
+      "Just plain content\nno frontmatter here\n",
+    );
+    const result = tryCommit();
+    expect(result.success).toBe(false);
+    expect(result.output).toContain("missing frontmatter");
+  });
+
+  test("allows valid frontmatter in system files without memory/ prefix", () => {
+    writeAndStage("system/human.md", `${VALID_FM}Block content here.\n`);
+    const result = tryCommit();
+    expect(result.success).toBe(true);
+  });
+
+  test("validates frontmatter for reference files without memory/ prefix", () => {
+    writeAndStage("reference/notes.md", "No frontmatter\n");
+    const result = tryCommit();
+    expect(result.success).toBe(false);
+    expect(result.output).toContain("missing frontmatter");
+  });
+
+  test("skips SKILL.md files inside skill directories", () => {
+    writeAndStage(
+      "skills/my-skill/SKILL.md",
+      "# My Skill\nNo frontmatter needed.\n",
+    );
+    const result = tryCommit();
+    expect(result.success).toBe(true);
+  });
+});
+
 describe("pre-commit hook: non-memory files", () => {
   test("ignores non-memory files", () => {
     writeAndStage("README.md", "---\nbogus: true\n---\n\nThis is fine.\n");