refactor: codebase audit cleanup — dead code, dedup, module splits

Multi-agent audit + aggressive cleanup across server/web/coder/booterm,
delivered behind a DEFER discipline so none of the in-flight files were
touched. Removes dead code/deps/columns, dedups server + coder helpers,
and splits the oversized modules (tools.ts, opencode-server.ts,
sentinel-summaries, turn.ts, TerminalPane.tsx) behind stable contracts.
Adds 78 parity/unit tests (server 587, coder 323); fixes two latent bugs
(ChatPane queue keys, FileViewerOverlay blank-line parity).

Intended tag: v2.7.12-audit-cleanup.

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

apps/coder/src/services/backends/warm-acp.ts

@@ -36,29 +36,15 @@
  */
 import { spawn, type ChildProcess } from 'node:child_process';
 import type { FastifyBaseLogger } from 'fastify';
-import {
-  ClientSideConnection,
-  type Client,
-  type SessionNotification,
-  type RequestPermissionRequest,
-  type RequestPermissionResponse,
-  type ReadTextFileRequest,
-  type ReadTextFileResponse,
-  type WriteTextFileRequest,
-  type WriteTextFileResponse,
-  type CreateTerminalRequest,
-  type CreateTerminalResponse,
-  type CreateElicitationRequest,
-  type CreateElicitationResponse,
-} from '@agentclientprotocol/sdk';
+import { ClientSideConnection, type Client } from '@agentclientprotocol/sdk';
 import type { Sql } from '../../db.js';
 import { resolveLaunchSpec } from '../acp-spawn.js';
 import { isTurnOkForStopReason } from './warm-acp-routing.js';
 import { getResolvedRegistry, type ResolvedProviderDef } from '../provider-config-registry.js';
 import { createAcpNdJsonStream } from '../acp-stream.js';
 import { mapSessionUpdate } from '../acp-event-map.js';
-import { readWorktreeTextFile, writeWorktreeTextFile } from '../acp-client-fs.js';
-import { waitForPermissionResponse, waitForElicitationResponse, cancelPendingPermission } from '../permission-waiter.js';
+import { buildAcpClient } from '../acp-client.js';
+import { cancelPendingPermission } from '../permission-waiter.js';
 import { type AcpToolSnapshot, synthesizeCanceledSnapshots } from '../acp-tool-snapshot.js';
 import type {
   AgentBackend,
@@ -211,47 +197,25 @@ export class WarmAcpBackend implements AgentBackend {
     );
   }
 
-  /** Build the ACP Client callbacks ONCE per connection. They read `this.activeTurn`
-   *  so each turn's events/permissions route to the right place — exactly the
-   *  opencode-server `activeTurn` pattern. Worktree-scoped FS like AcpStreamContext. */
+  /** Build the ACP Client callbacks ONCE per connection (shared `buildAcpClient`).
+   *  `resolveTurn` reads `this.activeTurn` at each callback so events/permissions
+   *  route to the live turn — exactly the prior behavior. The warm session always
+   *  has a non-empty `sessionId`, so the shared `taskId && sessionId` permission
+   *  gate is equivalent to the old `turn?.taskId` gate. */
   private buildClient(worktreePath: string): Client {
-    return {
-      sessionUpdate: async (params: SessionNotification): Promise<void> => {
-        const turn = this.activeTurn;
-        if (!turn) return; // between turns — drop (no orphan settles a future turn)
-        for (const event of mapSessionUpdate(params, turn.snapshots)) {
-          turn.onEvent(event);
-        }
-      },
-      requestPermission: async (params: RequestPermissionRequest): Promise<RequestPermissionResponse> => {
-        const turn = this.activeTurn;
-        if (turn?.taskId) {
-          // Route to the UI via the per-turn task id (same as the one-shot path).
-          return waitForPermissionResponse(turn.taskId, turn.sessionId, this.agent, turn.modeId, params);
-        }
-        const firstOption = params.options[0];
-        if (firstOption) return { outcome: { outcome: 'selected', optionId: firstOption.optionId } };
-        return { outcome: { outcome: 'cancelled' } };
-      },
-      readTextFile: async (params: ReadTextFileRequest): Promise<ReadTextFileResponse> => {
-        const content = await readWorktreeTextFile(worktreePath, params.path, params.line, params.limit);
-        return { content };
-      },
-      writeTextFile: async (params: WriteTextFileRequest): Promise<WriteTextFileResponse> => {
-        await writeWorktreeTextFile(worktreePath, params.path, params.content);
-        return {};
-      },
-      createTerminal: async (_params: CreateTerminalRequest): Promise<CreateTerminalResponse> => {
-        return { terminalId: 'noop' };
-      },
-      unstable_createElicitation: async (params: CreateElicitationRequest): Promise<CreateElicitationResponse> => {
-        const turn = this.activeTurn;
-        if (turn?.taskId) {
-          return waitForElicitationResponse(turn.taskId, turn.sessionId, this.agent, turn.modeId, params);
-        }
-        return { action: 'decline' };
-      },
-    };
+    return buildAcpClient(worktreePath, () => {
+      const turn = this.activeTurn;
+      if (!turn) return null;
+      return {
+        taskId: turn.taskId,
+        sessionId: turn.sessionId,
+        modeId: turn.modeId,
+        agent: this.agent,
+        onSessionUpdate: (params) => {
+          for (const event of mapSessionUpdate(params, turn.snapshots)) turn.onEvent(event);
+        },
+      };
+    });
   }
 
   // ─── ensureSession: create-or-reuse the warm session (2.1) ───────────────────
@@ -303,6 +267,14 @@ export class WarmAcpBackend implements AgentBackend {
       return { ok: false, error: 'warm-acp: no live ACP connection' };
     }
 
+    // v2.7 busy-assert: one in-flight turn per warm session. The dispatcher
+    // serializes turns per (chat, agent), so this never fires in normal dispatch —
+    // but a second concurrent prompt would silently overwrite `activeTurn` and
+    // orphan the first turn, so reject instead.
+    if (this.activeTurn) {
+      return { ok: false, error: 'warm-acp: session already has an in-flight turn' };
+    }
+
     const snapshots = new Map<string, AcpToolSnapshot>();
     // taskId routes permission/elicitation prompts back to the UI. The dispatcher
     // passes it (plus mode) on the per-turn PromptCtx; permission-waiter keys on it.