Fix pre-existing frontend TypeScript build errors

Type the commit metadata blob — new Note and CommitMetadata interfaces
in types/index.ts — so commit.metadata.notes resolves to Note[] instead
of unknown. This fixes the three CommitDetailPage errors where .length,
.map, and the JSX child type all failed against an unknown/{}-typed
notes field.

Normalize the structured-task list to strings at the rows() call in
ChatWorkspacePage so the string-list renderer receives string[] rather
than (string | StructuredTask)[].

No behavior change. npm run build (tsc -b + vite build) and tsc --noEmit
are now clean.

frontend/src/pages/ChatWorkspacePage.tsx

@@ -25,6 +25,7 @@ import {
   reviewCheckpoint,
 } from '../api/client';
 import type { Artifact, ChatSession, Commit, CompareResponse, CheckpointReviewResponse, HeadState, TurnEvent, Repo, ProviderStatus } from '../types';
+import { normalizeTask } from '../types';
 import {
   Check,
   Copy,
@@ -626,7 +627,7 @@ function CheckpointDetailPanel({
       )}
       {rows(commit.decisions ?? [], 'Decisions')}
       {rows(commit.assumptions ?? [], 'Assumptions')}
-      {rows(commit.tasks ?? [], 'Tasks')}
+      {rows((commit.tasks ?? []).map(t => normalizeTask(t).text), 'Tasks')}
       {rows(commit.open_questions ?? [], 'Open Questions')}
       {rows(commit.entities ?? [], 'Entities')}
 

frontend/src/pages/CommitDetailPage.tsx

@@ -267,7 +267,7 @@ export function CommitDetailPage() {
               {commit.metadata?.notes && commit.metadata.notes.length > 0 && (
                 <FieldBlock label="Notes">
                   <div className="space-y-2">
-                    {commit.metadata.notes.map((n: any, i: number) => (
+                    {commit.metadata.notes.map((n, i) => (
                       <div key={n.id || i} className="text-sm">
                         <div className="flex items-center gap-2 mb-0.5">
                           {n.kind && n.kind !== 'note' && (

frontend/src/types/index.ts

@@ -98,6 +98,22 @@ export interface Artifact {
   content: string;
 }
 
+/** An additive founder/agent annotation on a checkpoint. */
+export interface Note {
+  id: string;
+  author: string;
+  text: string;
+  kind: string;
+  created_at: string;
+}
+
+/** Commit metadata blob. `notes` are additive annotations; the open index
+ *  signature preserves room for other backend-written keys (e.g. session_id). */
+export interface CommitMetadata {
+  notes?: Note[];
+  [key: string]: unknown;
+}
+
 export interface Commit {
   id: string;
   repo_id: string;
@@ -117,7 +133,7 @@ export interface Commit {
   artifacts: Artifact[];
   context_blob: Record<string, unknown>;
   raw_source_text: string | null;
-  metadata: Record<string, unknown>;
+  metadata: CommitMetadata;
   created_at: string;
 }
 /** Delta between a commit and its parent, used for the diff view on CommitDetailPage */