fix(gsd): add codebase validation in validatePreferences so preferences are not silently dropped

The codebase preferences block was accepted as a known key but never
validated or assigned in validatePreferences(), causing all user-configured
codebase defaults to be silently discarded. Adds validation for
exclude_patterns (string[]), max_files (positive int), and collapse_threshold
(positive int) with unknown-key warnings and 4 new tests.

src/resources/extensions/gsd/preferences-validation.ts

@@ -857,5 +857,50 @@ export function validatePreferences(preferences: GSDPreferences): {
     }
   }
 
+  // ─── Codebase Map ──────────────────────────────────────────────────
+  if (preferences.codebase !== undefined) {
+    if (typeof preferences.codebase === "object" && preferences.codebase !== null) {
+      const cb = preferences.codebase as Record<string, unknown>;
+      const validCb: import("./preferences-types.js").CodebaseMapPreferences = {};
+
+      if (cb.exclude_patterns !== undefined) {
+        if (Array.isArray(cb.exclude_patterns) && cb.exclude_patterns.every((p: unknown) => typeof p === "string")) {
+          validCb.exclude_patterns = cb.exclude_patterns as string[];
+        } else {
+          errors.push("codebase.exclude_patterns must be an array of strings");
+        }
+      }
+      if (cb.max_files !== undefined) {
+        const mf = typeof cb.max_files === "number" ? cb.max_files : Number(cb.max_files);
+        if (Number.isFinite(mf) && mf >= 1) {
+          validCb.max_files = Math.floor(mf);
+        } else {
+          errors.push("codebase.max_files must be a positive integer");
+        }
+      }
+      if (cb.collapse_threshold !== undefined) {
+        const ct = typeof cb.collapse_threshold === "number" ? cb.collapse_threshold : Number(cb.collapse_threshold);
+        if (Number.isFinite(ct) && ct >= 1) {
+          validCb.collapse_threshold = Math.floor(ct);
+        } else {
+          errors.push("codebase.collapse_threshold must be a positive integer");
+        }
+      }
+
+      const knownCbKeys = new Set(["exclude_patterns", "max_files", "collapse_threshold"]);
+      for (const key of Object.keys(cb)) {
+        if (!knownCbKeys.has(key)) {
+          warnings.push(`unknown codebase key "${key}" — ignored`);
+        }
+      }
+
+      if (Object.keys(validCb).length > 0) {
+        validated.codebase = validCb;
+      }
+    } else {
+      errors.push("codebase must be an object");
+    }
+  }
+
   return { preferences: validated, errors, warnings };
 }

src/resources/extensions/gsd/tests/preferences.test.ts

@@ -461,3 +461,65 @@ test("experimental.rtk defaults to off in new project preferences", () => {
   assert.notEqual(prefs, null);
   assert.equal(prefs!.experimental?.rtk, undefined);
 });
+
+// ── Codebase Map Preferences ─────────────────────────────────────────────────
+
+test("codebase preferences validate and pass through correctly", () => {
+  const result = validatePreferences({
+    codebase: {
+      exclude_patterns: ["docs/", "fixtures/"],
+      max_files: 1000,
+      collapse_threshold: 15,
+    },
+  });
+  assert.equal(result.errors.length, 0);
+  assert.deepEqual(result.preferences.codebase?.exclude_patterns, ["docs/", "fixtures/"]);
+  assert.equal(result.preferences.codebase?.max_files, 1000);
+  assert.equal(result.preferences.codebase?.collapse_threshold, 15);
+});
+
+test("codebase preferences reject invalid types", () => {
+  const result = validatePreferences({
+    codebase: {
+      exclude_patterns: "not-an-array" as any,
+      max_files: -5,
+      collapse_threshold: 0,
+    },
+  });
+  assert.ok(result.errors.some(e => e.includes("exclude_patterns must be an array")));
+  assert.ok(result.errors.some(e => e.includes("max_files must be a positive")));
+  assert.ok(result.errors.some(e => e.includes("collapse_threshold must be a positive")));
+});
+
+test("codebase preferences warn on unknown keys", () => {
+  const result = validatePreferences({
+    codebase: {
+      exclude_patterns: ["docs/"],
+      unknown_key: true,
+    } as any,
+  });
+  assert.equal(result.errors.length, 0);
+  assert.ok(result.warnings.some(w => w.includes('unknown codebase key "unknown_key"')));
+  assert.deepEqual(result.preferences.codebase?.exclude_patterns, ["docs/"]);
+});
+
+test("codebase preferences parse from markdown frontmatter", () => {
+  const content = [
+    "---",
+    "version: 1",
+    "codebase:",
+    "  exclude_patterns:",
+    '    - "docs/"',
+    '    - ".cache/"',
+    "  max_files: 800",
+    "  collapse_threshold: 10",
+    "---",
+  ].join("\n");
+  const prefs = parsePreferencesMarkdown(content);
+  assert.notEqual(prefs, null);
+  const result = validatePreferences(prefs!);
+  assert.equal(result.errors.length, 0);
+  assert.deepEqual(result.preferences.codebase?.exclude_patterns, ["docs/", ".cache/"]);
+  assert.equal(result.preferences.codebase?.max_files, 800);
+  assert.equal(result.preferences.codebase?.collapse_threshold, 10);
+});