fix(#1575): address code review M1+M2+L1

M1: gate skills:'*' sentinel on unmodified-full profile (base profile must be
'full' AND no surface mods) so tiered profiles (core/standard) don't over-stage.
M2: thread resolveAttribution through capability-writer materialize opts; add
parity test variant with non-undefined Co-Authored-By attribution.
L1: remove redundant .agent.md filter condition (.endsWith('.md') already covers it).

src/capability-writer.cts

@@ -92,7 +92,7 @@ interface DesiredCapability {
 }
 
 interface SetCapabilityStateOptions {
-  materialize?: { runtime: string; scope: string };
+  materialize?: { runtime: string; scope: string; resolveAttribution?: (runtime: string) => string | null | undefined };
 }
 
 /**
@@ -352,8 +352,18 @@ function setCapabilityState(
       const layout = runtimeArtifactLayout.resolveRuntimeArtifactLayout(runtime, resolvedConfigDir, scope);
       const commandsGsdDir = _resolveCommandsGsdDir();
       const manifest = _resolveManifest(commandsGsdDir, resolvedConfigDir);
+      // #1575: applySurface now accepts opts.resolveAttribution so surface-path
+      // agents get the same Co-Authored-By trailer as the install path. The
+      // resolver is not threaded here yet — the CLI command handler does not have
+      // access to getCommitAttribution (which lives in bin/install.js). Until that
+      // is refactored into a shared module, surface-path agents for descriptor-
+      // driven runtimes will lack the Co-Authored-By trailer that install adds.
+      // Parity is proven when resolveAttribution IS provided (see
+      // tests/issue-1575-agent-descriptor-parity.test.cjs).
       // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
-      applySurface(resolvedConfigDir, layout, manifest, undefined, registry);
+      applySurface(resolvedConfigDir, layout, manifest, undefined, registry, opts?.materialize?.resolveAttribution
+        ? { resolveAttribution: opts.materialize.resolveAttribution }
+        : undefined);
     } catch (err: unknown) {
       const msg = err instanceof Error ? err.message : String(err);
       // Fix C: materialise was explicitly requested — a failure is an error (non-zero exit),

src/surface.cts

@@ -337,22 +337,27 @@ function applySurface(runtimeConfigDir: string, layout: Layout, manifest: Map<st
   const agentCtx: AgentCtx = { runtime: layout.runtime, pathPrefix: _pathPrefix, attribution: _attribution };
 
   const tempDirsToClean: string[] = [];
-  // #1575: When the surface has no state modifications (no .gsd-surface.json or
-  // it has no disabled clusters / explicit changes), pass the '*' sentinel for
-  // agents staging so ALL agents are staged — matching the install path which
-  // uses { skills: '*' }. Without this, agents not referenced by any skill's
-  // _calls_agents_ manifest entry would be silently dropped from the surface path.
+  // #1575: When the surface has no state modifications AND the base profile is
+  // 'full', pass the '*' sentinel for agents staging so ALL agents are staged —
+  // matching the install path which uses { skills: '*' }. Without this, agents
+  // not referenced by any skill's _calls_agents_ manifest entry would be silently
+  // dropped from the surface path. For tiered profiles (core/standard) or when
+  // surface mods exist, pass the resolved set so only the filtered subset stages.
   const _surfaceState = readSurface(layout.configDir);
+  const _baseProfileName = (_surfaceState && _surfaceState.baseProfile)
+    ? _surfaceState.baseProfile
+    : (readActiveProfile(layout.configDir) || 'full');
   const _hasSurfaceMods = !!_surfaceState && (
     _surfaceState.disabledClusters.length > 0 ||
     _surfaceState.explicitAdds.length > 0 ||
     _surfaceState.explicitRemoves.length > 0
   );
+  const _isUnmodifiedFull = _baseProfileName === 'full' && !_hasSurfaceMods;
   try {
     for (const kind of layout.kinds) {
       let staged: string;
       if (kind.kind === 'agents') {
-        const agentProfile = _hasSurfaceMods ? resolved : { ...resolved, skills: '*' as const };
+        const agentProfile = _isUnmodifiedFull ? { ...resolved, skills: '*' as const } : resolved;
         staged = kind.stage(agentProfile, agentCtx);
       } else {
         staged = kind.stage(resolved);
@@ -548,7 +553,7 @@ function _syncGsdDir(stagedDir: string, destDir: string, kind: ArtifactKind | st
     //   - namespaced command dirs: the whole dir is GSD-owned
     const shouldPruneAgents = !(kindName === 'agents' && (!manifest || manifest.size === 0));
     if (shouldPruneAgents) {
-      for (const file of fs.readdirSync(destDir).filter(f => f.endsWith('.md') || (isCopilotAgents && f.endsWith('.agent.md')))) {
+      for (const file of fs.readdirSync(destDir).filter(f => f.endsWith('.md'))) {
         if (kindName === 'agents' && !file.startsWith('gsd-')) continue;
         if (kindName === 'commands' && !namespacedByDir && kindPrefix && !file.startsWith(kindPrefix)) continue;
         if (!stagedDestNames.has(file)) {

tests/issue-1575-agent-descriptor-parity.test.cjs

@@ -98,7 +98,35 @@ describe('#1575 — golden-parity: surface path matches install path for descrip
           installContent,
           `${runtime}/${fileName}: surface content must be byte-identical to install content`,
         );
-      }
+  }
+
+  test('cursor with non-undefined attribution: surface agents byte-identical to install agents (M2 coverage)', (t) => {
+    // M2 regression guard: verify parity holds when resolveAttribution returns
+    // a real Co-Authored-By value, not just undefined. Proves the agentCtx
+    // threading is correct for both paths.
+    const attrResolver = () => 'Test Bot <test@example.com>';
+    const configDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-1575-attr-'));
+    t.after(() => { try { cleanup(configDir); } catch { /* best-effort */ } });
+
+    installRuntimeArtifacts('cursor', configDir, 'global', profile, attrResolver);
+
+    const agentsDir = path.join(configDir, 'agents');
+    const installSnap = snapshotAgents(agentsDir);
+    assert.ok(installSnap.size > 0, 'install must produce agents');
+
+    // Verify attribution was actually applied by install path
+    const firstContent = [...installSnap.values()][0];
+    assert.ok(firstContent.includes('Co-Authored-By: Test Bot'), 'install must apply Co-Authored-By');
+
+    const layout = resolveRuntimeArtifactLayout('cursor', configDir, 'global');
+    applySurface(configDir, layout, manifest, undefined, undefined, { resolveAttribution: attrResolver });
+
+    const surfaceSnap = snapshotAgents(agentsDir);
+    for (const [fileName, installContent] of installSnap) {
+      assert.strictEqual(surfaceSnap.get(fileName), installContent,
+        `cursor/${fileName}: content must be byte-identical with attribution`);
+    }
+  });
     });
   }