docs(changelog): v2.6.8-agent-attribution

CHANGELOG + roadmap shipped record (through v2.6.8) + openspec v2-6 Phase 1-UX checked off (U.1-U.6; Smoke U pending the frontend Docker rebuild).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes per release tag. Most recent on top, ordered by tag creation date (which matches the git history). Tag names follow `vMAJOR.MINOR.PATCH-slug` — the slug describes what shipped, so the tag name alone is enough to recall the batch.
 
+## v2.6.8-agent-attribution — 2026-05-31
+
+v2.6 Phase 1-UX: agent attribution + switch affordances over the already-shipped `pending_changes.agent` column and `agent_sessions` table (read+display, no new backend capability). **Backend:** `pending_changes.agent` is now stamped at every queue site (native write tools → `'boocode'`, dispatched external agents → the task's agent, manual RightRail create → `NULL`) and flows through `listPending`; a new `GET /api/sessions/:id/agent-sessions` route returns `[{agent,status,has_session,last_active_at}]` per `(chat,agent)` for the session's chats; and the opencode warm-server backend consumes opencode's `session.next.step.ended` events, accumulating `input_tokens`/`output_tokens`/`cost` onto the `agent_sessions` row (new columns, idempotent). **Frontend:** the BooCoder DiffPanel renders a per-row agent badge (provider icon + label; `null` → "manual") with a "Changes from X, Y" note when a pending set spans multiple agents, and the AgentComposerBar shows a resumed / history / new-session chip beside the Provider picker — gated on an optional `sessionId` prop so BooChat is unaffected — driven by a new `useAgentSessions` hook that refetches on message-complete; `providerIcon` was extracted to a shared `components/coder/providerIcons.tsx`. Built by three parallel subagents over disjoint file sets; web + coder typecheck clean, 165 coder tests pass (9 new across `opencode-usage` and `agent-sessions.routes`). U.6's persisted token totals are conversation-cumulative and not yet surfaced in the UI (deferred). Implements the U.1–U.6 "remaining" plan from the v2.6 openspec reconciliation; Phase 2 (warm ACP goose/qwen) + Phase 3 (lifecycle hardening) remain.
+
 ## v2.6.7-interrupt-guard — 2026-05-31
 
 Fixes a post-interrupt correctness bug in the `v2.6.1-phase1-opencode` warm-server backend, made one-click reachable by `v2.6.5-panes-tabs-composer`'s Send→Stop composer. `opencode-server.ts` settled an in-flight turn on opencode's `session.idle`/`session.error` by calling `activeTurn.settle()` on whatever turn currently held the session slot — but opencode emits one trailing terminal event for a *cancelled* turn after `client.session.abort()`, and those events carry only a `sessionID` (no turn id). So after the user hit Stop and immediately sent another message, the aborted turn's orphan `session.idle` settled the *new* turn early as success (Paseo hit and fixed the same class in `1d38aac`). The fix adds a small pure guard (`turn-guard.ts`: `armAbortGuard`/`noteTurnActivity`/`consumeTerminal` over a per-session `swallowNextTerminal` flag): abort arms it, the next terminal is swallowed once, and a new turn's first delta self-heals the flag so a never-arriving orphan can't strand a real turn. Implemented test-first — three regression tests in `turn-guard.test.ts` (swallow-the-orphan, settle-when-no-abort, self-heal); full coder suite green (156 passed). This is the F.1 "fix-next" item from the v2.6 openspec reconciliation; Phase 1-UX / Phase 2 / Phase 3 remain.

apps/coder/src/index.ts

@@ -25,6 +25,7 @@ import { setInferenceContext, clearInferenceContext } from './services/tools/inf
 import { registerMessageRoutes } from './routes/messages.js';
 import { registerSkillRoutes } from './routes/skills.js';
 import { registerPendingRoutes } from './routes/pending.js';
+import { registerAgentSessionRoutes } from './routes/agent-sessions.js';
 import { registerTaskRoutes } from './routes/tasks.js';
 import { registerInboxRoutes } from './routes/inbox.js';
 import { registerStatsRoutes } from './routes/stats.js';
@@ -191,6 +192,7 @@ async function main() {
   registerMessageRoutes(app, sql, broker, inferenceApi);
   registerSkillRoutes(app, sql, broker, inferenceApi);
   registerPendingRoutes(app, sql);
+  registerAgentSessionRoutes(app, sql);
   registerTaskRoutes(app, sql, inferenceApi);
   registerInboxRoutes(app, sql);
   registerStatsRoutes(app, sql);

apps/coder/src/routes/__tests__/agent-sessions.routes.test.ts

@@ -0,0 +1,75 @@
+import { describe, it, expect } from 'vitest';
+import Fastify, { type FastifyInstance } from 'fastify';
+import { registerAgentSessionRoutes } from '../agent-sessions.js';
+import type { Sql } from '../../db.js';
+
+// Mock the porsager surface this route uses: a tagged-template `sql` dispatched by
+// query substring. Two queries: the session-existence check and the agent_sessions
+// JOIN. We return post-coercion shapes (booleans/strings) exactly as porsager would
+// hand them to the route — `has_session` already a JS boolean, `last_active_at` a
+// string|null — so the asserted JSON matches the API contract end-to-end.
+interface MockState {
+  sessionExists: boolean;
+  rows: Array<{ agent: string; status: string; has_session: boolean; last_active_at: string | null }>;
+}
+
+function mockSql(state: MockState): Sql {
+  return ((strings: TemplateStringsArray) => {
+    const q = strings.join('');
+    if (q.includes('SELECT id FROM sessions')) {
+      return Promise.resolve(state.sessionExists ? [{ id: 'session-1' }] : []);
+    }
+    if (q.includes('FROM agent_sessions')) {
+      return Promise.resolve(state.rows);
+    }
+    return Promise.resolve([]);
+  }) as unknown as Sql;
+}
+
+function buildApp(state: MockState): FastifyInstance {
+  const app = Fastify();
+  registerAgentSessionRoutes(app, mockSql(state));
+  return app;
+}
+
+describe('GET /api/sessions/:id/agent-sessions', () => {
+  it('returns the per-(chat,agent) rows in the contracted shape', async () => {
+    const app = buildApp({
+      sessionExists: true,
+      rows: [
+        { agent: 'opencode', status: 'active', has_session: true, last_active_at: '2026-05-31T12:00:00.000Z' },
+        { agent: 'goose', status: 'idle', has_session: false, last_active_at: null },
+      ],
+    });
+    const res = await app.inject({ method: 'GET', url: '/api/sessions/session-1/agent-sessions' });
+    expect(res.statusCode).toBe(200);
+    const body = res.json();
+    expect(Array.isArray(body)).toBe(true);
+    expect(body).toEqual([
+      { agent: 'opencode', status: 'active', has_session: true, last_active_at: '2026-05-31T12:00:00.000Z' },
+      { agent: 'goose', status: 'idle', has_session: false, last_active_at: null },
+    ]);
+    // Contract field types.
+    expect(typeof body[0].agent).toBe('string');
+    expect(typeof body[0].status).toBe('string');
+    expect(typeof body[0].has_session).toBe('boolean');
+    expect(body[1].last_active_at).toBeNull();
+    await app.close();
+  });
+
+  it('returns an empty array when the session has no agent_sessions rows', async () => {
+    const app = buildApp({ sessionExists: true, rows: [] });
+    const res = await app.inject({ method: 'GET', url: '/api/sessions/session-1/agent-sessions' });
+    expect(res.statusCode).toBe(200);
+    expect(res.json()).toEqual([]);
+    await app.close();
+  });
+
+  it('404s when the session does not exist', async () => {
+    const app = buildApp({ sessionExists: false, rows: [] });
+    const res = await app.inject({ method: 'GET', url: '/api/sessions/nope/agent-sessions' });
+    expect(res.statusCode).toBe(404);
+    expect(res.json()).toEqual({ error: 'session not found' });
+    await app.close();
+  });
+});

apps/coder/src/routes/agent-sessions.ts

@@ -0,0 +1,51 @@
+import type { FastifyInstance } from 'fastify';
+import type { Sql } from '../db.js';
+
+// v2.6 Phase 1-UX (design §9b): chat-scoped "resumed vs new session" indicator.
+// `agent_sessions` is keyed (chat_id, agent) — the tab/chat is the agent-context
+// unit (P1.5-b). The route param is a SESSION id, so we resolve every chat in the
+// session and return the union of their agent_sessions rows. A session with two
+// opencode tabs yields two rows (one per chat); the frontend keys the chip per
+// chat, but the wire shape is a flat per-(chat,agent) list.
+//
+// has_session = agent_session_id IS NOT NULL — i.e. a native backend session id
+// (opencode/ACP) was created and stored, so switching back resumes rather than
+// starts fresh.
+export interface AgentSessionRow {
+  agent: string;
+  status: string;
+  has_session: boolean;
+  last_active_at: string | null;
+}
+
+export function registerAgentSessionRoutes(app: FastifyInstance, sql: Sql): void {
+  // GET /api/sessions/:sessionId/agent-sessions — list the agent-session rows for
+  // every chat in the session (drives the AgentComposerBar resumed/new chip).
+  app.get<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/agent-sessions',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+
+      const session = await sql<{ id: string }[]>`SELECT id FROM sessions WHERE id = ${sessionId}`;
+      if (session.length === 0) {
+        reply.code(404);
+        return { error: 'session not found' };
+      }
+
+      // Join through chats so the session-scoped param resolves to its (chat,agent)
+      // rows. last_active_at first → the frontend reads the freshest activity.
+      const rows = await sql<AgentSessionRow[]>`
+        SELECT
+          a.agent AS agent,
+          a.status AS status,
+          (a.agent_session_id IS NOT NULL) AS has_session,
+          a.last_active_at AS last_active_at
+        FROM agent_sessions a
+        JOIN chats c ON c.id = a.chat_id
+        WHERE c.session_id = ${sessionId}
+        ORDER BY a.last_active_at DESC NULLS LAST, a.agent ASC
+      `;
+      return rows;
+    },
+  );
+}

apps/coder/src/routes/pending.ts

@@ -90,6 +90,8 @@ export function registerPendingRoutes(app: FastifyInstance, sql: Sql): void {
           parsed.data.file_path,
           parsed.data.content,
           projectRoot,
+          // Manual RightRail create — no agent staged it; renders as "manual".
+          null,
         );
         return change;
       } catch (err) {

apps/coder/src/schema.sql

@@ -131,6 +131,17 @@ END $$;
 -- v2.6: config fingerprint for stale-session detection (auto-recover on model change).
 ALTER TABLE agent_sessions ADD COLUMN IF NOT EXISTS config_hash TEXT;
 
+-- v2.6 Phase 1-UX (U.6): opencode token/cost usage, ACCUMULATED per (chat_id, agent).
+-- opencode's warm server emits `session.next.step.ended` once per LLM step (several
+-- per multi-tool turn) carrying {tokens{input,output,reasoning,cache},cost}. We sum
+-- each step's normalized {input,output,cost} onto the session row — running totals
+-- for the whole conversation context, not last-step. Backend-only; no route/UI yet.
+-- input_tokens folds in cache read+write; output_tokens folds in reasoning (see
+-- backends/opencode-usage.ts). Defaults 0 so accumulation (col + delta) is well-defined.
+ALTER TABLE agent_sessions ADD COLUMN IF NOT EXISTS input_tokens BIGINT NOT NULL DEFAULT 0;
+ALTER TABLE agent_sessions ADD COLUMN IF NOT EXISTS output_tokens BIGINT NOT NULL DEFAULT 0;
+ALTER TABLE agent_sessions ADD COLUMN IF NOT EXISTS cost DOUBLE PRECISION NOT NULL DEFAULT 0;
+
 -- ─── P1.5-b (corrected): worktrees entity + re-key agent_sessions to (chat_id, agent) ───
 -- The TAB (a chat) is the context unit: two opencode tabs in one session = two
 -- independent contexts sharing one worktree. So agent_sessions keys on

apps/coder/src/services/backends/__tests__/opencode-usage.test.ts

@@ -0,0 +1,51 @@
+import { describe, it, expect } from 'vitest';
+import { stepEndedToUsage } from '../opencode-usage.js';
+
+describe('stepEndedToUsage (U.6)', () => {
+  it('folds cache read+write into input and reasoning into output', () => {
+    const u = stepEndedToUsage({
+      cost: 0.0123,
+      tokens: { input: 100, output: 50, reasoning: 20, cache: { read: 10, write: 5 } },
+    });
+    expect(u).toEqual({ input: 115, output: 70, cost: 0.0123 });
+  });
+
+  it('handles a step with no cache and no reasoning', () => {
+    const u = stepEndedToUsage({
+      cost: 0,
+      tokens: { input: 8, output: 4, reasoning: 0, cache: { read: 0, write: 0 } },
+    });
+    expect(u).toEqual({ input: 8, output: 4, cost: 0 });
+  });
+
+  it('is defensive against a missing tokens block', () => {
+    const u = stepEndedToUsage({ cost: 0.5 } as never);
+    expect(u).toEqual({ input: 0, output: 0, cost: 0.5 });
+  });
+
+  it('is defensive against undefined props', () => {
+    expect(stepEndedToUsage(undefined)).toEqual({ input: 0, output: 0, cost: 0 });
+  });
+
+  it('drops NaN / negative noise to zero rather than poisoning the accumulated total', () => {
+    const u = stepEndedToUsage({
+      cost: Number.NaN,
+      tokens: {
+        input: -5,
+        output: Number.NaN,
+        reasoning: 3,
+        cache: { read: Number.POSITIVE_INFINITY, write: 2 },
+      },
+    });
+    // input: (-5→0) + (Inf→0) + 2 = 2; output: (NaN→0) + 3 = 3; cost: NaN→0
+    expect(u).toEqual({ input: 2, output: 3, cost: 0 });
+  });
+
+  it('rounds fractional token counts', () => {
+    const u = stepEndedToUsage({
+      cost: 1.5,
+      tokens: { input: 10.6, output: 4.4, reasoning: 0, cache: { read: 0, write: 0 } },
+    });
+    expect(u).toEqual({ input: 11, output: 4, cost: 1.5 });
+  });
+});

apps/coder/src/services/backends/opencode-server.ts

@@ -38,6 +38,7 @@ import type { ToolCallStatus } from '@agentclientprotocol/sdk';
 import type { Sql } from '../../db.js';
 import type { AcpToolSnapshot } from '../acp-tool-snapshot.js';
 import { armAbortGuard, noteTurnActivity, consumeTerminal } from './turn-guard.js';
+import { stepEndedToUsage, type StepUsage } from './opencode-usage.js';
 import type {
   AgentBackend,
   AgentEvent,
@@ -282,6 +283,19 @@ export class OpenCodeServerBackend implements AgentBackend {
         st.activeTurn.onEvent({ type: 'tool_update', toolCall: snap });
         return;
       }
+      // ─── per-step usage (U.6) — token/cost accounting for opencode sessions ──
+      case 'session.next.step.ended': {
+        const p = ev.properties;
+        const st = this.byOpencodeId.get(p.sessionID);
+        if (!st?.activeTurn) return;
+        this.bumpActivity(st);
+        // Accumulate this step's normalized usage onto the (chat_id, agent) row.
+        // Fire-and-forget: a DB hiccup must not stall the turn. opencode emits this
+        // once per LLM step, so a multi-tool turn sums several deltas.
+        const usage = stepEndedToUsage(p);
+        void this.accumulateUsage(st, usage);
+        return;
+      }
       // ─── message.part.* — terminal/post-hoc events (dedup gate) ────────────
       case 'message.part.delta': {
         const p = ev.properties;
@@ -428,6 +442,33 @@ export class OpenCodeServerBackend implements AgentBackend {
     }
   }
 
+  // ─── per-step usage persistence (U.6) ────────────────────────────────────────
+
+  /**
+   * Accumulate one `session.next.step.ended`'s normalized usage onto the session's
+   * agent_sessions row, keyed by the resumed `agent_session_id` (unique per active
+   * row — the dispatcher's `(chat_id, agent)` lookup wrote it). Running totals for
+   * the whole conversation context (not last-step). Zero-delta steps are skipped to
+   * avoid a no-op write. Errors are swallowed: usage telemetry must never fail a turn.
+   */
+  private async accumulateUsage(st: SessionState, u: StepUsage): Promise<void> {
+    if (u.input === 0 && u.output === 0 && u.cost === 0) return;
+    try {
+      await this.sql`
+        UPDATE agent_sessions SET
+          input_tokens = input_tokens + ${u.input},
+          output_tokens = output_tokens + ${u.output},
+          cost = cost + ${u.cost}
+        WHERE agent_session_id = ${st.agentSessionId}
+      `;
+    } catch (err) {
+      this.log.warn(
+        { err: errMsg(err), agentSessionId: st.agentSessionId },
+        'opencode-server: failed to persist step usage (non-fatal)',
+      );
+    }
+  }
+
   // ─── ensureSession: create-or-resume against agent_sessions (1.5) ────────────
 
   async ensureSession(sessionId: string, opts: EnsureSessionOpts): Promise<AgentSessionHandle> {

apps/coder/src/services/backends/opencode-usage.ts

@@ -0,0 +1,77 @@
+/**
+ * v2.6 Phase 1-UX (U.6) — pure mapper for opencode's per-step usage event.
+ *
+ * opencode's warm server emits `session.next.step.ended` once per completed LLM
+ * step (so a multi-tool turn fires it several times). Its `properties` carry the
+ * step's token + cost accounting:
+ *
+ *   {
+ *     timestamp: number;
+ *     sessionID: string;
+ *     finish: string;
+ *     cost: number;                                  // USD for this step
+ *     tokens: {
+ *       input: number; output: number; reasoning: number;
+ *       cache: { read: number; write: number };
+ *     };
+ *     snapshot?: string;
+ *   }
+ *
+ * (Verified against @opencode-ai/sdk@1.15.12 — `EventSessionNextStepEnded` in
+ * `dist/v2/gen/types.gen.d.ts`, a member of the `Event` union the SSE loop
+ * switches on.)
+ *
+ * We normalize to the review's target slice `{input, output, cost}` (the
+ * provider-agnostic `AgentUsage` shape lands later). cache read/write tokens are
+ * folded into `input` so the persisted input count reflects the real context the
+ * model billed for; reasoning tokens are folded into `output` since that's what
+ * the provider counts them as for generation. This keeps the persisted totals a
+ * faithful sum of what opencode reported, without inventing extra columns yet.
+ */
+
+/** The `properties` shape of a `session.next.step.ended` event (subset we read). */
+export interface StepEndedProps {
+  cost: number;
+  tokens: {
+    input: number;
+    output: number;
+    reasoning: number;
+    cache: { read: number; write: number };
+  };
+}
+
+/** Normalized per-step usage delta persisted onto the agent_sessions row. */
+export interface StepUsage {
+  input: number;
+  output: number;
+  cost: number;
+}
+
+/** Coerce a possibly-missing/NaN number to a non-negative finite integer (tokens). */
+function n(v: unknown): number {
+  const x = typeof v === 'number' ? v : Number(v);
+  return Number.isFinite(x) && x > 0 ? Math.round(x) : 0;
+}
+
+/** Coerce a possibly-missing/NaN number to a non-negative finite float (cost USD). */
+function f(v: unknown): number {
+  const x = typeof v === 'number' ? v : Number(v);
+  return Number.isFinite(x) && x > 0 ? x : 0;
+}
+
+/**
+ * Map a `session.next.step.ended` payload → the normalized `{input, output, cost}`
+ * delta. Defensive against missing/partial token blocks (the wire is trusted but
+ * we never want a NaN to poison the accumulated DB total). `input` folds in cache
+ * read+write; `output` folds in reasoning.
+ */
+export function stepEndedToUsage(props: Partial<StepEndedProps> | undefined): StepUsage {
+  const t = props?.tokens;
+  const cacheRead = n(t?.cache?.read);
+  const cacheWrite = n(t?.cache?.write);
+  return {
+    input: n(t?.input) + cacheRead + cacheWrite,
+    output: n(t?.output) + n(t?.reasoning),
+    cost: f(props?.cost),
+  };
+}

apps/coder/src/services/dispatcher.ts

@@ -441,10 +441,11 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
       const diff = await diffWorktree(worktreePath, projectPath, { signal: ac.signal });
 
       if (diff) {
-        // Queue a single pending_change entry with the full unified diff
+        // Queue a single pending_change entry with the full unified diff, stamped
+        // with the dispatched agent for DiffPanel attribution (v2.6 Phase 1-UX).
         await sql`
-          INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
-          VALUES (${sessionId}, ${taskId}, ${projectPath}, 'edit', ${diff})
+          INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff, agent)
+          VALUES (${sessionId}, ${taskId}, ${projectPath}, 'edit', ${diff}, ${agent})
         `;
         log.info({ taskId, diffLength: diff.length }, 'dispatcher: diff queued as pending change');
       } else {

apps/coder/src/services/pending_changes.ts

@@ -13,6 +13,10 @@ export interface PendingChange {
   operation: 'create' | 'edit' | 'delete';
   diff: string;
   status: 'pending' | 'applied' | 'rejected' | 'reverted';
+  // v2.6 Phase 1-UX: which agent staged this change (DiffPanel attribution).
+  // Native boocode write tools stamp 'boocode'; the manual RightRail create path
+  // passes null (renders as "manual"). NULL on legacy rows queued pre-v2.6.
+  agent: string | null;
   created_at: string;
 }
 
@@ -34,13 +38,17 @@ export async function queueEdit(
   oldString: string,
   newString: string,
   projectRoot: string,
+  // v2.6 Phase 1-UX: attribution. Defaults to 'boocode' because the only callers
+  // that omit it are the native write tools (edit_file/create_file/delete_file).
+  // Pass null explicitly for the manual RightRail create path.
+  agent: string | null = 'boocode',
 ): Promise<PendingChange> {
   const resolved = resolveWritePath(projectRoot, filePath);
   const diff = JSON.stringify({ old: oldString, new: newString });
 
   const [row] = await sql<PendingChange[]>`
-    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
-    VALUES (${sessionId}, ${taskId}, ${resolved}, 'edit', ${diff})
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff, agent)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'edit', ${diff}, ${agent})
     RETURNING *
   `;
   return row!;
@@ -53,12 +61,15 @@ export async function queueCreate(
   filePath: string,
   content: string,
   projectRoot: string,
+  // See queueEdit: defaults to 'boocode' for the native write tools; the manual
+  // RightRail create route passes null.
+  agent: string | null = 'boocode',
 ): Promise<PendingChange> {
   const resolved = resolveWritePath(projectRoot, filePath);
 
   const [row] = await sql<PendingChange[]>`
-    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
-    VALUES (${sessionId}, ${taskId}, ${resolved}, 'create', ${content})
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff, agent)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'create', ${content}, ${agent})
     RETURNING *
   `;
   return row!;
@@ -70,12 +81,14 @@ export async function queueDelete(
   taskId: string | null,
   filePath: string,
   projectRoot: string,
+  // See queueEdit: defaults to 'boocode' for the native write tools.
+  agent: string | null = 'boocode',
 ): Promise<PendingChange> {
   const resolved = resolveWritePath(projectRoot, filePath);
 
   const [row] = await sql<PendingChange[]>`
-    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
-    VALUES (${sessionId}, ${taskId}, ${resolved}, 'delete', '')
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff, agent)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'delete', '', ${agent})
     RETURNING *
   `;
   return row!;

apps/web/src/api/client.ts

@@ -25,6 +25,17 @@ import type {
   WorkspaceState,
 } from './types';
 
+// v2.6 Phase 1-UX §9b: chat-scoped agent-session rows. Returned by
+// GET /api/coder/sessions/:id/agent-sessions; drives the AgentComposerBar
+// resumed/new-session chip via useAgentSessions. `has_session` is true when a
+// resumable backend session id exists for that agent in the chat.
+export interface AgentSessionInfo {
+  agent: string;
+  status: string;
+  has_session: boolean;
+  last_active_at: string | null;
+}
+
 export class ApiError extends Error {
   constructor(
     public status: number,
@@ -363,6 +374,11 @@ export const api = {
       request<CoderMessageWire[]>(
         `/api/coder/sessions/${sessionId}/messages${chatId ? `?chat_id=${encodeURIComponent(chatId)}` : ''}`,
       ),
+    // v2.6 Phase 1-UX §9b: per-(chat,agent) backend-session state for the
+    // resumed/new-session chip. Chat-scoped (NOT foldable into the project-level
+    // provider snapshot). Proxied to boocoder at /api/sessions/:id/agent-sessions.
+    agentSessions: (sessionId: string) =>
+      request<AgentSessionInfo[]>(`/api/coder/sessions/${sessionId}/agent-sessions`),
     skillInvoke: (
       sessionId: string,
       paneId: string,

apps/web/src/components/AgentComposerBar.tsx

@@ -1,9 +1,10 @@
 import { useEffect, useMemo, useRef, useState } from 'react';
-import { Check, ChevronDown, RefreshCw, Loader2, Shield, Brain, Bird, Bot, Dog, Terminal as TermIcon } from 'lucide-react';
-import { ClaudeIcon, OpenCodeIcon } from '@/components/icons/ProviderIcons';
+import { Check, ChevronDown, RefreshCw, Loader2, Shield, Brain, Bot } from 'lucide-react';
 import { api } from '@/api/client';
 import type { AgentSessionConfig, ProviderSnapshotEntry, AgentCommand } from '@/api/types';
 import { useProviderSnapshot, refreshProviderSnapshot } from '@/hooks/useProviderSnapshot';
+import { providerIcon } from '@/components/coder/providerIcons';
+import { useAgentSessions } from '@/hooks/useAgentSessions';
 import {
   DropdownMenu,
   DropdownMenuContent,
@@ -172,9 +173,36 @@ interface Props {
   onChange: (next: AgentSessionConfig) => void;
   onProviderCommandsChange?: (commands: AgentCommand[]) => void;
   connected?: boolean;
+  // v2.6 Phase 1-UX §9b: chat id for the resumed/new-session chip. Optional so
+  // BooChat and any other AgentComposerBar caller renders no chip and is
+  // otherwise unaffected. When present + connected + the chat has ≥1 prior
+  // turn, a chip right of the Provider picker reports whether switching to the
+  // current provider resumes an agent session, replays history (boocode), or
+  // starts fresh.
+  sessionId?: string;
+  // True once the chat has at least one prior turn — gates the chip so it stays
+  // hidden on a brand-new chat. Defaults to false (no chip).
+  hasPriorTurn?: boolean;
 }
 
-export function AgentComposerBar({ projectPath, value, onChange, onProviderCommandsChange, connected }: Props) {
+// Relative-time formatter for the resumed-chip title (e.g. "3m ago").
+function relativeTime(iso: string | null): string {
+  if (!iso) return 'unknown';
+  const then = new Date(iso).getTime();
+  if (Number.isNaN(then)) return 'unknown';
+  const diffMs = Date.now() - then;
+  if (diffMs < 0) return 'just now';
+  const sec = Math.floor(diffMs / 1000);
+  if (sec < 60) return 'just now';
+  const min = Math.floor(sec / 60);
+  if (min < 60) return `${min}m ago`;
+  const hr = Math.floor(min / 60);
+  if (hr < 24) return `${hr}h ago`;
+  const day = Math.floor(hr / 24);
+  return `${day}d ago`;
+}
+
+export function AgentComposerBar({ projectPath, value, onChange, onProviderCommandsChange, connected, sessionId, hasPriorTurn }: Props) {
   const allEntries = useProviderSnapshot(projectPath);
   // 5.5 — the composer picker only offers ENABLED providers that are ready (or
   // still loading). Disabled (enabled:false) and unavailable/error providers are
@@ -186,6 +214,13 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
   );
   const [refreshing, setRefreshing] = useState(false);
 
+  // v2.6 Phase 1-UX §9b: chat-scoped agent-session rows for the resumed/new
+  // chip. Hook is unconditional (hooks rule); it self-no-ops when sessionId is
+  // undefined or the chat has no prior turn, so BooChat callers cost nothing.
+  const { sessions: agentSessions } = useAgentSessions(
+    sessionId && hasPriorTurn ? sessionId : undefined,
+  );
+
   const hydratedRef = useRef(false);
 
   useEffect(() => {
@@ -294,21 +329,30 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
     );
   }
 
-  const providerIcon = (name: string) => {
-    switch (name) {
-      case 'claude': return <ClaudeIcon size={13} className="shrink-0" />;
-      case 'opencode': return <OpenCodeIcon size={13} className="shrink-0" />;
-      case 'goose': return <Bird size={13} className="shrink-0" />;
-      case 'qwen': return <TermIcon size={13} className="shrink-0" />;
-      default: return <Dog size={13} className="shrink-0" />;
-    }
-  };
-
   const providerOptions = entries.map((e) => ({ id: e.name, label: e.label }));
   const modeOptions = (currentEntry?.modes ?? []).map((m) => ({ id: m.id, label: m.label }));
   const modelOptions = (currentEntry?.models ?? []).map((m) => ({ id: m.id, label: m.label }));
   const thinkingOpts = thinkingOptions.map((t) => ({ id: t.id, label: t.label }));
 
+  // v2.6 Phase 1-UX §9b: resumed / history / new-session chip. Only meaningful
+  // when this is a real chat (sessionId), the WS is connected, and the chat has
+  // ≥1 prior turn — otherwise render nothing so fresh chats and non-coder
+  // callers stay clean.
+  const sessionRow = agentSessions.find((s) => s.agent === value.provider);
+  const sessionChip: { label: string; title: string } | null =
+    sessionId && hasPriorTurn && connected
+      ? value.provider === 'boocode'
+        ? // Native boocode never holds an agent_sessions row — it reconstructs
+          // the conversation from the chat transcript each turn.
+          { label: 'history', title: 'BooCode replays the chat transcript each turn' }
+        : sessionRow?.has_session
+          ? {
+              label: 'resumed',
+              title: `Resuming ${value.provider} · last active ${relativeTime(sessionRow.last_active_at)}`,
+            }
+          : { label: 'new session', title: `${value.provider} starts a fresh session this turn` }
+      : null;
+
   return (
     <div className="flex flex-wrap items-center gap-1 px-2 py-1 border-b border-border bg-muted/20 shrink-0">
       <CompactPicker
@@ -322,6 +366,14 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
             : providerIcon(value.provider)
         }
       />
+      {sessionChip && (
+        <span
+          title={sessionChip.title}
+          className="inline-flex items-center rounded-full border border-border bg-muted/40 px-1.5 py-0.5 text-[10px] font-medium text-muted-foreground shrink-0"
+        >
+          {sessionChip.label}
+        </span>
+      )}
       <CompactPicker
         label="Mode"
         value={value.modeId ?? ''}

apps/web/src/components/coder/providerIcons.tsx

@@ -0,0 +1,56 @@
+// Shared provider icon + label helpers for BooCoder UI.
+//
+// Single source of truth for the per-provider glyph used in the
+// AgentComposerBar picker and the CoderPane DiffPanel agent-attribution
+// badges (v2.6 Phase 1-UX §9a/§9b). Extracted from AgentComposerBar's local
+// `providerIcon` switch so both call sites stay in sync.
+
+import type { ReactNode } from 'react';
+import { Bird, Dog, Terminal as TermIcon } from 'lucide-react';
+import { ClaudeIcon, OpenCodeIcon } from '@/components/icons/ProviderIcons';
+
+/**
+ * Glyph for a provider/agent name. Mirrors AgentComposerBar's original
+ * `providerIcon` switch verbatim — `boocode` (native) falls through to the
+ * neutral dog like any unmapped name, preserving the composer's prior look.
+ * Sized to match the picker (13px) by default; pass a different size for
+ * inline badges.
+ */
+export function providerIcon(name: string | null, size = 13): ReactNode {
+  switch (name) {
+    case 'claude':
+      return <ClaudeIcon size={size} className="shrink-0" />;
+    case 'opencode':
+      return <OpenCodeIcon size={size} className="shrink-0" />;
+    case 'goose':
+      return <Bird size={size} className="shrink-0" />;
+    case 'qwen':
+      return <TermIcon size={size} className="shrink-0" />;
+    default:
+      return <Dog size={size} className="shrink-0" />;
+  }
+}
+
+/**
+ * Human label for a provider/agent name. `null` → "manual" (a RightRail-staged
+ * change with no dispatching agent, per §9a). Unknown names pass through
+ * verbatim so a future provider still reads sensibly.
+ */
+export function providerLabel(name: string | null): string {
+  switch (name) {
+    case null:
+      return 'manual';
+    case 'boocode':
+      return 'BooCode';
+    case 'opencode':
+      return 'opencode';
+    case 'claude':
+      return 'Claude';
+    case 'goose':
+      return 'goose';
+    case 'qwen':
+      return 'Qwen';
+    default:
+      return name;
+  }
+}

apps/web/src/components/panes/CoderPane.tsx

@@ -16,6 +16,8 @@ import { toast } from 'sonner';
 import { isSlashCommandToken, mergeCommandsByName, parseSlashInput, slashQuery } from '@/lib/slash-command';
 import { mergeWireToolCall } from '@/lib/coder-tools';
 import { CoderMessageList, type CoderTimelineWire } from '@/components/panes/CoderMessageList';
+import { providerIcon, providerLabel } from '@/components/coder/providerIcons';
+import { refreshAgentSessions } from '@/hooks/useAgentSessions';
 import { cn } from '@/lib/utils';
 
 // ---------------------------------------------------------------------------
@@ -56,6 +58,10 @@ interface PendingChange {
   diff?: string;
   new_content?: string;
   status: 'pending' | 'approved' | 'rejected';
+  // v2.6 Phase 1-UX §9a: which agent staged this change. 'boocode' for native
+  // write tools, the dispatched agent for worktree edits, null for a manual
+  // RightRail-staged create (renders as a neutral "manual" badge).
+  agent: string | null;
 }
 
 interface Props {
@@ -394,6 +400,15 @@ function DiffPanel({
 }) {
   const pending = changes.filter((c) => c.status === 'pending');
 
+  // v2.6 Phase 1-UX §9a: when pending changes span >1 distinct agent, surface a
+  // one-line "Changes from <a>, <b>" note so mixed provenance is obvious. Null
+  // (manual) counts as its own bucket and renders as "manual".
+  const distinctAgents = Array.from(new Set(pending.map((c) => c.agent)));
+  const mixedNote =
+    distinctAgents.length > 1
+      ? `Changes from ${distinctAgents.map((a) => providerLabel(a)).join(', ')}`
+      : null;
+
   return (
     <div className="flex flex-col h-full border-t border-border">
       <div className="flex items-center justify-between px-3 py-1.5 border-b border-border bg-muted/30">
@@ -410,6 +425,11 @@ function DiffPanel({
           <RefreshCw size={12} className={loading ? 'animate-spin' : ''} />
         </button>
       </div>
+      {mixedNote && (
+        <div className="px-3 py-1 border-b border-border bg-muted/10 text-[11px] text-muted-foreground truncate">
+          {mixedNote}
+        </div>
+      )}
       <div className="flex-1 overflow-y-auto">
         {pending.length === 0 ? (
           <div className="flex items-center justify-center h-full text-sm text-muted-foreground">
@@ -420,14 +440,25 @@ function DiffPanel({
             {pending.map((change) => (
               <div key={change.id} className="px-3 py-2">
                 <div className="flex items-center justify-between mb-1">
-                  <span className="text-xs font-mono text-foreground truncate flex-1 mr-2">
+                  <span className="text-xs font-mono text-foreground truncate flex-1 mr-2 inline-flex items-center min-w-0">
+                    <span
+                      className="inline-flex items-center gap-1 rounded border border-border bg-muted/40 px-1 py-px mr-1.5 text-[10px] font-medium text-muted-foreground shrink-0"
+                      title={
+                        change.agent === null
+                          ? 'Manually staged (no dispatching agent)'
+                          : `Staged by ${providerLabel(change.agent)}`
+                      }
+                    >
+                      {providerIcon(change.agent, 11)}
+                      <span>{providerLabel(change.agent)}</span>
+                    </span>
                     <span className={cn(
-                      'inline-block w-1.5 h-1.5 rounded-full mr-1.5',
+                      'inline-block w-1.5 h-1.5 rounded-full mr-1.5 shrink-0',
                       change.operation === 'create' && 'bg-green-500',
                       change.operation === 'modify' && 'bg-yellow-500',
                       change.operation === 'delete' && 'bg-red-500',
                     )} />
-                    {change.file_path}
+                    <span className="truncate">{change.file_path}</span>
                   </span>
                   <div className="flex items-center gap-1 shrink-0">
                     <button
@@ -586,15 +617,24 @@ export function CoderPane({
   // dispatch returns — so queueing/stop must key on this combined signal.
   const generating = sending || activeTaskId !== null;
 
-  // Refresh pending changes when a message_complete arrives
+  // Refresh pending changes (and agent-session state for the §9b chip) when a
+  // message_complete arrives — same trigger usePendingChanges already uses.
   useEffect(() => {
     const lastAssistant = [...messages].reverse().find(
       (m): m is CoderMessage => m.role === 'assistant',
     );
     if (lastAssistant?.status === 'complete') {
       refresh();
+      void refreshAgentSessions(sessionId);
     }
-  }, [messages, refresh]);
+  }, [messages, refresh, sessionId]);
+
+  // The §9b chip only shows once the chat has ≥1 prior turn (a completed
+  // assistant message). Hidden on a brand-new chat.
+  const hasPriorTurn = useMemo(
+    () => messages.some((m) => m.role === 'assistant' && (m as CoderMessage).status === 'complete'),
+    [messages],
+  );
 
   // Poll fallbacks when WS is disconnected (reconnect uses WS as source of truth)
   useEffect(() => {
@@ -834,6 +874,8 @@ export function CoderPane({
         onChange={setAgentConfig}
         onProviderCommandsChange={handleProviderCommandsChange}
         connected={connected}
+        sessionId={sessionId}
+        hasPriorTurn={hasPriorTurn}
       />
       {/* Chat area — BooChat-style timeline (text + tool runs as siblings) */}
       <div className="flex-1 min-h-0 flex flex-col">

apps/web/src/hooks/useAgentSessions.ts

@@ -0,0 +1,88 @@
+// v2.6 Phase 1-UX §9b — chat-scoped agent-session state.
+//
+// Reads GET /api/coder/sessions/:id/agent-sessions (the per-(chat,agent)
+// backend-session rows) and drives the AgentComposerBar resumed/new-session
+// chip. Module-singleton external store keyed by sessionId — same shape as
+// useProviderSnapshot — so the two consumers (CoderPane, which owns the
+// message_complete WS signal, and AgentComposerBar, which renders the chip)
+// share one cache and one fetch per chat. CoderPane calls
+// refreshAgentSessions(sessionId) on each message_complete (the same trigger
+// usePendingChanges already keys off); the chip then reflects the freshly
+// resumed/created session.
+
+import { useEffect, useSyncExternalStore } from 'react';
+import { api, type AgentSessionInfo } from '@/api/client';
+
+type Entry = {
+  data: AgentSessionInfo[];
+  inflight: Promise<AgentSessionInfo[]> | null;
+};
+
+const store = new Map<string, Entry>();
+const listeners = new Set<() => void>();
+const EMPTY: AgentSessionInfo[] = [];
+
+function notify(): void {
+  for (const fn of listeners) fn();
+}
+
+function subscribe(fn: () => void): () => void {
+  listeners.add(fn);
+  return () => listeners.delete(fn);
+}
+
+function getEntry(sessionId: string): Entry {
+  let entry = store.get(sessionId);
+  if (!entry) {
+    entry = { data: EMPTY, inflight: null };
+    store.set(sessionId, entry);
+  }
+  return entry;
+}
+
+async function doFetch(sessionId: string): Promise<AgentSessionInfo[]> {
+  const data = await api.coder.agentSessions(sessionId);
+  const entry = getEntry(sessionId);
+  entry.data = data;
+  entry.inflight = null;
+  notify();
+  return data;
+}
+
+function ensureLoaded(sessionId: string): void {
+  const entry = getEntry(sessionId);
+  if (entry.data !== EMPTY || entry.inflight) return;
+  entry.inflight = doFetch(sessionId).catch(() => {
+    // boocoder may be down or the chat has no agent-session rows yet; treat as
+    // empty (the chip falls back to "new session" / hides).
+    const e = getEntry(sessionId);
+    e.inflight = null;
+    return EMPTY;
+  });
+}
+
+/** Force a refetch for one chat. Wired to message_complete by CoderPane. */
+export function refreshAgentSessions(sessionId: string): Promise<AgentSessionInfo[]> {
+  const entry = getEntry(sessionId);
+  entry.inflight = null;
+  return doFetch(sessionId);
+}
+
+/**
+ * Chat-scoped agent-session rows. Pass `undefined` to opt out (no fetch, empty
+ * result) — AgentComposerBar does this for BooChat callers and fresh chats so
+ * the chip stays hidden. Fetches on mount (and on sessionId change); refetch on
+ * message_complete is driven externally via refreshAgentSessions.
+ */
+export function useAgentSessions(sessionId: string | undefined): {
+  sessions: AgentSessionInfo[];
+} {
+  const sessions = useSyncExternalStore(
+    subscribe,
+    () => (sessionId ? getEntry(sessionId).data : EMPTY),
+  );
+  useEffect(() => {
+    if (sessionId) ensureLoaded(sessionId);
+  }, [sessionId]);
+  return { sessions: sessionId ? sessions : EMPTY };
+}

boocode_roadmap.md

@@ -348,7 +348,7 @@ Per-session Docker sandbox spawned by BooCoder on first write. Only project path
 
 -----
 
-## Shipped (v2.2.2–v2.6.7 — interactive ACP, provider lifecycle, persistent agent sessions, workspace UX)
+## Shipped (v2.2.2–v2.6.8 — interactive ACP, provider lifecycle, persistent agent sessions, workspace UX)
 
 All tags `vMAJOR.MINOR.PATCH-slug`, monotonic per minor, assigned at ship time (planning slugs differ — see the numbering-discipline note below). `CHANGELOG.md` is the canonical per-tag record. **Note on numbering divergence:** the *planned-feature* "v2.3 — Provider lifecycle" actually shipped under the **v2.5.4–v2.5.13** tags; the *planned-feature* "v2.4 — BooCoder as ACP agent" remains **unshipped** even though v2.4.0/v2.4.1 *tags* shipped unrelated content (Unsloth lifts, sidecar routing). The patch-tag thread and the conceptual-milestone thread have diverged — read tags as the ship record, the `## v2.x` feature sections below as the milestone plan. The v2.3.0–v2.5.1 tags were never CHANGELOG-backfilled; summarized here from commit bodies.
 
@@ -382,6 +382,7 @@ All tags `vMAJOR.MINOR.PATCH-slug`, monotonic per minor, assigned at ship time (
 - `v2.6.5-panes-tabs-composer` — **workspace UX batch (BooChat panes/tabs/composer + the persistence that backs it).** *Panes/tabs:* open a chat in a fresh pane (ChatTabBar "Open in new pane" + fork-beside-original via a new `open_chat_in_new_pane` event), per-pane `[+]` → New BooChat/BooTerm/BooCode menu, closing a chat pane relocates its tabs (in order) to the oldest chat/empty pane (reopen strips restored chatIds from every live pane first → no dup), stable session-scoped tab numbers (assigned on open, retired on close, never reused, map-keyed render), and the empty/landing pane became a real session history (open + separately-fetched archived chats). Removed the per-message "Open in pane" artifact button. *Persistence:* `sessions.workspace_panes` widened from bare `WorkspacePane[]` → a `WorkspaceState` envelope (`panes` + `tabNumbers`/`nextTabNumber` + `closedPaneStack`); PATCH validator zod-unions legacy-array-or-envelope and migrates on write; `session_workspace_updated` WS frame widened (web+server byte-identical, parity test green). *Composer:* morphing **Send → Stop → Queue** button keyed on `sending || activeTaskId` (folds in the standalone Stop pill, adds `cancelTask`); pasted chips trail the typed text so a leading slash stays first. *Tooling:* new read-only `read_tab_by_number` tool + an optional `ToolExecCtx` (`{ sql, sessionId }`) 4th arg on `ToolDef.execute`
 - `v2.6.6-claude-md` — docs-only CLAUDE.md session-learnings from the v2.6.5 batch: the `WorkspaceState` envelope migration, the `ToolExecCtx` plumb (`read_tab_by_number` as reference), the two-schema-files-one-DB ownership split + idempotent `confdeltype` FK-action-flip pattern, and React-StrictMode nested-`setState` idempotency
 - `v2.6.7-interrupt-guard` — **F.1 fix:** post-interrupt stale-terminal bug in the opencode warm-server backend (one-click reachable since `v2.6.5`'s Stop button). opencode emits one trailing `session.idle`/`session.error` for a cancelled turn (sessionID only, no turn id) that settled the *next* turn early as success. Pure per-session guard (`backends/turn-guard.ts` — arm-on-abort / swallow-one-orphan / self-heal-on-activity) wired into `opencode-server.ts`; 3 regression tests (TDD). First item of the v2.6 openspec "remaining" plan; Phase 1-UX / 2 / 3 still open
+- `v2.6.8-agent-attribution` — **v2.6 Phase 1-UX** (U.1–U.6), built by 3 parallel subagents over disjoint files. Backend: `pending_changes.agent` stamped at every queue site + flows through `listPending`; new `GET /api/sessions/:id/agent-sessions` route; opencode warm-server consumes `session.next.step.ended` → accumulates `input_tokens`/`output_tokens`/`cost` on `agent_sessions`. Frontend: DiffPanel per-row agent badges + multi-agent note; AgentComposerBar resumed/history/new-session chip (gated on optional `sessionId`, BooChat unaffected); shared `providerIcons.tsx` + `useAgentSessions` hook. 9 new tests; web+coder tsc clean. **Backend deploys via boocoder restart; frontend awaits the `boocode` Docker rebuild.** Phase 2/3 remain
 
 -----
 

openspec/changes/v2-6-persistent-agent-sessions/tasks.md

@@ -29,20 +29,16 @@ ACP follows; hardening last.
 - [x] P1.5-a **Per-session SSE** (`v2.6.2-delete-guard-and-sse`): one `event.subscribe({directory})` per live opencode session, each with an `AbortController`; `sessionID` demux guard + zombie-loop fix — replaces task 1.3's single global loop. Bundled: session-delete work-loss guard (`/worktree-risk`).
 - [x] P1.5-b **Re-key `agent_sessions` → `(chat_id, agent)`** + first-class `worktrees` table (`v2.6.3-chatkey-and-skills`); `tasks.chat_id` threaded; `runOpenCodeServerTask` resolve-or-creates a chat for session-less creators; cross-chunk dcp-strip. FK convergence to `SET NULL` (`v2.6.4-agent-sessions-fk`).
 
-## Phase 1 (UX) — Attribution & switch affordances (design §9) — ⬜ REMAINING (pure read+display over already-shipped `pending_changes.agent` + `agent_sessions`)
+## Phase 1 (UX) — Attribution & switch affordances (design §9) — ✅ SHIPPED `v2.6.8-agent-attribution` (Smoke U pending live frontend deploy)
 
-- [ ] U.1 Stamp `pending_changes.agent` at queue time (worktree path → task agent;
-      native write tools → `'boocode'`; manual RightRail create → NULL).
-- [ ] U.2 Add `agent` to `listPending` response + frontend `PendingChange` type.
-- [ ] U.3 Extract `providerIcon()` to a shared helper; DiffPanel renders an agent badge
-      per row + a "Changes from X, Y" note when the pending set spans >1 agent (§9a).
-- [ ] U.4 `GET /api/sessions/:id/agent-sessions` route + `api.coder.agentSessions` +
-      `useAgentSessions(sessionId)` (refetch on `message_complete`) (§9b).
-- [ ] U.5 `AgentComposerBar` optional `sessionId` prop → resumed / history / new-session
-      chip beside the Provider picker; hidden on fresh chats and other callers (§9b).
-- [ ] U.6 Consume opencode `session.next.step.ended` `{tokens, cost}` → fill ctx/token usage for opencode sessions (SDK already installed; closes the "no usage for external agents" gap; surface beside the §9b chip). Source: `boocode_code_review_v2.md` §1 #8, design §10.
+- [x] U.1 Stamp `pending_changes.agent` at queue time — native tools default `'boocode'`, dispatched external → `task.agent`, manual RightRail → `NULL` (`pending_changes.ts`, `dispatcher.ts`).
+- [x] U.2 `agent` flows through `listPending` + backend & frontend `PendingChange` types.
+- [x] U.3 Shared `components/coder/providerIcons.tsx`; DiffPanel per-row agent badge + "Changes from X, Y" multi-agent note (§9a).
+- [x] U.4 `GET /api/sessions/:id/agent-sessions` route + `api.coder.agentSessions` + `useAgentSessions` hook (refetch on message-complete) (§9b).
+- [x] U.5 `AgentComposerBar` optional `sessionId` prop → resumed/history/new-session chip; hidden on fresh chats + other callers (§9b).
+- [x] U.6 Consume opencode `session.next.step.ended` → accumulate `input_tokens`/`output_tokens`/`cost` on `agent_sessions` (new cols). Backend persist only; UI surfacing deferred.
 - [ ] **Smoke U:** stage edits with opencode then boocode → DiffPanel badges each row to the
-      right agent; composer shows "resumed" when re-selecting opencode, "new session" for goose.
+      right agent; composer shows "resumed" when re-selecting opencode, "new session" for goose. *(pending live frontend deploy — Docker container rebuild)*
 
 ## Phase 2 — Warm ACP backend (goose, qwen) — ⬜ REMAINING
 
@@ -102,7 +98,7 @@ ACP follows; hardening last.
 ## Remaining — recommended order (implementation plan, 2026-05-31)
 
 1. ~~**F.1 interrupt-bug fix**~~ — ✅ shipped `v2.6.7-interrupt-guard` (3 regression tests, TDD).
-2. **Phase 1-UX** (U.1–U.6) — pure read+display over already-shipped `pending_changes.agent` + `agent_sessions`; no dispatch-logic or backend change, so it ships value on data that already exists. U.6 (token/ctx usage) rides the same opencode SSE.
+2. ~~**Phase 1-UX** (U.1–U.6)~~ — ✅ shipped `v2.6.8-agent-attribution` (3 parallel agents, disjoint files; 9 new tests). Smoke U pending the frontend Docker rebuild.
 3. **Phase 2 — warm ACP, qwen first then goose** — qwen has a validated `--acp` reference; goose's missing resume is the open design question, so qwen de-risks the pattern. Smoke 2 + 2b (the switch round-trip success criterion).
 4. **Phase 3 — lifecycle hardening** — lift openchamber's state machine; do crash-recovery (3.1/3.2/3.6) + worktree reaper (3.3/3.4 + LRU) together (shared supervision loop). Closes the two ⬜ success criteria (server-crash recovery, close→cleanup).
 5. **Tests T.1–T.3 + `BOOCODER.md` (D.1 remainder)** — backfill alongside each phase, not at the end.