v2.0.1: ACP dispatch + PTY fallback + worktree management

Phase 5 of v2.0. External agent dispatch via SSH to host.

ACP dispatch (acp-dispatch.ts): spawns agent via SSH with JSON-RPC
stdio pipe. Wraps opencode/goose in ACP mode. Captures structured
events (file operations, tool calls) mapped to parts taxonomy.
Falls back to PTY if ACP handshake fails.

PTY dispatch (pty-dispatch.ts): raw SSH spawn for agents without ACP
support (claude, pi). Captures stdout/stderr as plain text. Simpler
but less structured than ACP.

SSH helper (ssh.ts): shared spawn wrapper for SSH commands to
samkintop@100.114.205.53 (Tailscale IP, same as booterm). Uses
openssh-client installed in the runtime Dockerfile stage.

Worktree management (worktrees.ts): createWorktree (git worktree add
via SSH), diffWorktree (git diff HEAD...task-branch), cleanupWorktree
(git worktree remove --force). One worktree per task at
/tmp/booworktrees/<taskId>.

Dispatcher updated: checks available_agents.supports_acp to pick
transport. Path B flow: create worktree → dispatch agent → diff
worktree → queue diff into pending_changes → cleanup worktree →
mark task complete.

Agent probe updated: probes via SSH to find host-installed agents
(which opencode && opencode --version over SSH).

Dockerfile: openssh-client added to runtime stage.
Config: SSH_HOST env var (default 100.114.205.53).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/coder/Dockerfile

@@ -23,7 +23,7 @@ RUN pnpm deploy --filter=@boocode/coder --prod --legacy /out/coder
 
 
 FROM node:20-bookworm-slim AS runtime
-RUN apt-get update && apt-get install -y --no-install-recommends ripgrep git && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install -y --no-install-recommends ripgrep git openssh-client && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 
 COPY --from=builder /out/coder ./

apps/coder/package.json

@@ -12,6 +12,7 @@
     "test": "vitest run"
   },
   "dependencies": {
+    "@agentclientprotocol/sdk": "^0.22.1",
     "@boocode/server": "workspace:*",
     "@fastify/static": "^7.0.4",
     "@fastify/websocket": "^10.0.1",

apps/coder/src/config.ts

@@ -23,6 +23,9 @@ const ConfigSchema = z.object({
   GITEA_TOKEN: z.string().optional(),
   GITEA_SSH_HOST: z.string().default('100.114.205.53:2222'),
   MCP_CONFIG_PATH: z.string().optional(),
+  // SSH access to the host for external agent dispatch (Phase 5)
+  BOOCODER_SSH_HOST: z.string().default('100.114.205.53'),
+  BOOCODER_SSH_USER: z.string().default('samkintop'),
 });
 
 export type Config = z.infer<typeof ConfigSchema>;

apps/coder/src/services/acp-dispatch.ts

@@ -0,0 +1,271 @@
+/**
+ * ACP dispatch — runs ACP-capable agents (opencode, goose) on the host via SSH.
+ *
+ * Uses the @agentclientprotocol/sdk to establish a structured JSON-RPC session
+ * with the agent subprocess. The SSH tunnel provides stdio transport.
+ *
+ * Flow:
+ * 1. SSH to host, start `opencode acp` (or `goose acp`) in the worktree
+ * 2. Wrap SSH child's stdin/stdout into NDJSON streams
+ * 3. Create a ClientSideConnection from the SDK
+ * 4. Initialize → newSession → prompt(task)
+ * 5. Collect session updates (tool calls, text output)
+ * 6. On prompt completion → return collected output
+ */
+import type { FastifyBaseLogger } from 'fastify';
+import { Readable, Writable } from 'node:stream';
+import {
+  ClientSideConnection,
+  ndJsonStream,
+  type Client,
+  type SessionNotification,
+  type RequestPermissionRequest,
+  type RequestPermissionResponse,
+  type ReadTextFileRequest,
+  type ReadTextFileResponse,
+  type WriteTextFileRequest,
+  type WriteTextFileResponse,
+  type CreateTerminalRequest,
+  type CreateTerminalResponse,
+} from '@agentclientprotocol/sdk';
+import { sshSpawn } from './ssh.js';
+
+export interface AcpDispatchResult {
+  exitCode: number;
+  output: string;
+  toolCalls: Array<{ title: string; input: unknown; output?: unknown }>;
+  stopReason: string;
+}
+
+export interface AcpDispatchOpts {
+  agent: string;
+  task: string;
+  worktreePath: string;
+  model?: string;
+  signal?: AbortSignal;
+  log: FastifyBaseLogger;
+}
+
+/** Map agent name to the ACP command it exposes. */
+function acpCommand(agent: string): string | null {
+  switch (agent) {
+    case 'opencode':
+      return 'opencode acp';
+    case 'goose':
+      return 'goose acp';
+    default:
+      return null;
+  }
+}
+
+/**
+ * Convert a Node.js Readable stream to a web ReadableStream<Uint8Array>.
+ */
+function nodeReadableToWeb(nodeStream: NodeJS.ReadableStream): ReadableStream<Uint8Array> {
+  return new ReadableStream<Uint8Array>({
+    start(controller) {
+      nodeStream.on('data', (chunk: Buffer) => {
+        controller.enqueue(new Uint8Array(chunk));
+      });
+      nodeStream.on('end', () => {
+        controller.close();
+      });
+      nodeStream.on('error', (err) => {
+        controller.error(err);
+      });
+    },
+    cancel() {
+      if ('destroy' in nodeStream && typeof (nodeStream as Readable).destroy === 'function') {
+        (nodeStream as Readable).destroy();
+      }
+    },
+  });
+}
+
+/**
+ * Convert a Node.js Writable stream to a web WritableStream<Uint8Array>.
+ */
+function nodeWritableToWeb(nodeStream: NodeJS.WritableStream): WritableStream<Uint8Array> {
+  return new WritableStream<Uint8Array>({
+    write(chunk) {
+      return new Promise<void>((resolve, reject) => {
+        const ok = (nodeStream as Writable).write(chunk, (err) => {
+          if (err) reject(err);
+        });
+        if (ok) resolve();
+        else (nodeStream as Writable).once('drain', resolve);
+      });
+    },
+    close() {
+      return new Promise<void>((resolve) => {
+        (nodeStream as Writable).end(resolve);
+      });
+    },
+    abort() {
+      (nodeStream as Writable).destroy();
+    },
+  });
+}
+
+/**
+ * Dispatch a task to an ACP-capable agent via SSH.
+ *
+ * Opens a structured ACP session, sends the task as a prompt, and collects
+ * all session updates. Returns the collected output and tool calls.
+ */
+export async function dispatchViaAcp(opts: AcpDispatchOpts): Promise<AcpDispatchResult> {
+  const { agent, task, worktreePath, signal, log } = opts;
+
+  const cmd = acpCommand(agent);
+  if (!cmd) {
+    return {
+      exitCode: 1,
+      output: `Agent '${agent}' does not support ACP.`,
+      toolCalls: [],
+      stopReason: 'error',
+    };
+  }
+
+  // Spawn SSH with the ACP command running in the worktree
+  const escapedPath = worktreePath.replace(/'/g, "'\\''");
+  const fullCommand = `cd '${escapedPath}' && ${cmd}`;
+
+  log.info({ agent, worktreePath }, 'acp-dispatch: spawning');
+  const child = sshSpawn(fullCommand);
+
+  // Wire up abort
+  let killed = false;
+  const cleanup = () => {
+    if (!killed) {
+      killed = true;
+      child.kill('SIGTERM');
+      setTimeout(() => child.kill('SIGKILL'), 5_000);
+    }
+  };
+
+  if (signal) {
+    if (signal.aborted) {
+      cleanup();
+      return { exitCode: 130, output: 'Aborted before start', toolCalls: [], stopReason: 'cancelled' };
+    }
+    signal.addEventListener('abort', cleanup, { once: true });
+  }
+
+  try {
+    // Create web streams from the child process stdio
+    const inputStream = nodeReadableToWeb(child.stdout!);
+    const outputStream = nodeWritableToWeb(child.stdin!);
+
+    // Create the NDJSON ACP stream
+    const stream = ndJsonStream(outputStream, inputStream);
+
+    // Collected session updates
+    const textChunks: string[] = [];
+    const toolCalls: Array<{ title: string; input: unknown; output?: unknown }> = [];
+
+    // Create client-side connection — we are the "client" (editor), the agent is remote
+    const connection = new ClientSideConnection(
+      (_agentInterface): Client => ({
+        // Handle session updates from the agent
+        async sessionUpdate(params: SessionNotification): Promise<void> {
+          const update = params.update;
+          if (update.sessionUpdate === 'agent_message_chunk') {
+            // ContentChunk with content: ContentBlock
+            const content = update.content;
+            if (content.type === 'text' && 'text' in content) {
+              textChunks.push((content as { text: string }).text);
+            }
+          } else if (update.sessionUpdate === 'tool_call') {
+            toolCalls.push({
+              title: update.title,
+              input: update.rawInput,
+            });
+          } else if (update.sessionUpdate === 'tool_call_update') {
+            const last = toolCalls[toolCalls.length - 1];
+            if (last && update.rawOutput !== undefined) {
+              last.output = update.rawOutput;
+            }
+          }
+        },
+
+        // Permission requests — auto-approve by selecting the first option (worktree is isolated)
+        async requestPermission(params: RequestPermissionRequest): Promise<RequestPermissionResponse> {
+          // Select the first available option to auto-approve
+          const firstOption = params.options[0];
+          if (firstOption) {
+            return {
+              outcome: { outcome: 'selected', optionId: firstOption.optionId },
+            };
+          }
+          // No options available — cancel
+          return { outcome: { outcome: 'cancelled' } };
+        },
+
+        // File system operations — let the agent handle them directly in the worktree
+        async readTextFile(_params: ReadTextFileRequest): Promise<ReadTextFileResponse> {
+          return { content: '' };
+        },
+        async writeTextFile(_params: WriteTextFileRequest): Promise<WriteTextFileResponse> {
+          return {};
+        },
+        async createTerminal(_params: CreateTerminalRequest): Promise<CreateTerminalResponse> {
+          return { terminalId: 'noop' };
+        },
+      }),
+      stream,
+    );
+
+    // Initialize the connection
+    // ProtocolVersion is a number in this SDK version
+    const initResult = await connection.initialize({
+      protocolVersion: 1,
+      clientInfo: { name: 'boocoder', version: '2.0.1' },
+      clientCapabilities: {},
+    });
+    log.info({ agentInfo: initResult.agentInfo }, 'acp-dispatch: initialized');
+
+    // Create a new session
+    const session = await connection.newSession({
+      cwd: worktreePath,
+      mcpServers: [],
+    });
+    log.info({ sessionId: session.sessionId }, 'acp-dispatch: session created');
+
+    // Send the prompt
+    const promptResult = await connection.prompt({
+      sessionId: session.sessionId,
+      prompt: [{ type: 'text', text: task }],
+    });
+
+    const stopReason = promptResult.stopReason ?? 'end_turn';
+    log.info({ agent, stopReason, toolCallCount: toolCalls.length }, 'acp-dispatch: prompt completed');
+
+    // Clean shutdown
+    await connection.closeSession({ sessionId: session.sessionId }).catch(() => {});
+
+    return {
+      exitCode: 0,
+      output: textChunks.join(''),
+      toolCalls,
+      stopReason,
+    };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    log.error({ agent, err: message }, 'acp-dispatch: error');
+    return {
+      exitCode: 1,
+      output: message,
+      toolCalls: [],
+      stopReason: 'error',
+    };
+  } finally {
+    if (signal) signal.removeEventListener('abort', cleanup);
+    cleanup();
+
+    // Wait for child to exit
+    await new Promise<void>((resolve) => {
+      child.on('close', resolve);
+      setTimeout(resolve, 3_000);
+    });
+  }
+}

apps/coder/src/services/agent-probe.ts

@@ -1,9 +1,6 @@
-import { execFile } from 'node:child_process';
-import { promisify } from 'node:util';
 import type { Sql } from '../db.js';
 import type { FastifyBaseLogger } from 'fastify';
-
-const execFileAsync = promisify(execFile);
+import { sshExec } from './ssh.js';
 
 const KNOWN_AGENTS: Array<{ name: string; supportsAcp: boolean }> = [
   { name: 'opencode', supportsAcp: true },
@@ -12,38 +9,60 @@ const KNOWN_AGENTS: Array<{ name: string; supportsAcp: boolean }> = [
   { name: 'pi', supportsAcp: false },
 ];
 
+/**
+ * Probe for available agents on the HOST via SSH.
+ *
+ * The boocoder container can't run agents locally — they live on the host.
+ * We SSH to the host (same mechanism BooTerm uses) and check which agent
+ * binaries are on PATH.
+ */
 export async function probeAgents(sql: Sql, log: FastifyBaseLogger): Promise<void> {
-  log.info('agent-probe: scanning PATH for known agents');
+  log.info('agent-probe: scanning HOST for known agents via SSH');
 
   for (const agent of KNOWN_AGENTS) {
     try {
-      // Check if the agent binary is on PATH
-      const { stdout: whichOut } = await execFileAsync('which', [agent.name], { timeout: 5_000 });
-      const installPath = whichOut.trim();
-      if (!installPath) continue;
+      // Check if the agent binary is on the host's PATH
+      const whichResult = await sshExec(`which ${agent.name}`, { timeoutMs: 10_000 });
+      const installPath = whichResult.stdout.trim();
+      if (whichResult.exitCode !== 0 || !installPath) continue;
 
       // Get version
       let version: string | null = null;
       try {
-        const { stdout: verOut } = await execFileAsync(agent.name, ['--version'], { timeout: 10_000 });
-        version = verOut.trim().slice(0, 100);
+        const verResult = await sshExec(`${agent.name} --version`, { timeoutMs: 15_000 });
+        if (verResult.exitCode === 0) {
+          version = verResult.stdout.trim().slice(0, 100);
+        }
       } catch {
         // Some agents may not support --version — that's fine
       }
 
+      // For ACP-capable agents, verify ACP mode actually works
+      let supportsAcp = agent.supportsAcp;
+      if (supportsAcp) {
+        try {
+          const acpCheck = await sshExec(`${agent.name} acp --help`, { timeoutMs: 10_000 });
+          supportsAcp = acpCheck.exitCode === 0;
+        } catch {
+          supportsAcp = false;
+        }
+      }
+
       // UPSERT into available_agents
       await sql`
         INSERT INTO available_agents (name, install_path, version, supports_acp, last_probed_at)
-        VALUES (${agent.name}, ${installPath}, ${version}, ${agent.supportsAcp}, clock_timestamp())
+        VALUES (${agent.name}, ${installPath}, ${version}, ${supportsAcp}, clock_timestamp())
         ON CONFLICT (name) DO UPDATE SET
           install_path = EXCLUDED.install_path,
           version = EXCLUDED.version,
           supports_acp = EXCLUDED.supports_acp,
           last_probed_at = EXCLUDED.last_probed_at
       `;
-      log.info({ agent: agent.name, version, installPath }, 'agent-probe: found');
-    } catch {
-      // Agent not found on PATH — skip silently
+      log.info({ agent: agent.name, version, installPath, supportsAcp }, 'agent-probe: found on host');
+    } catch (err) {
+      // SSH failed or agent not found — skip silently
+      const msg = err instanceof Error ? err.message : String(err);
+      log.debug({ agent: agent.name, err: msg }, 'agent-probe: not found or SSH failed');
     }
   }
 

apps/coder/src/services/dispatcher.ts

@@ -2,6 +2,9 @@ import type { Sql } from '../db.js';
 import type { FastifyBaseLogger } from 'fastify';
 import type { Broker } from '@boocode/server/broker';
 import type { Config } from '../config.js';
+import { createWorktree, diffWorktree, cleanupWorktree } from './worktrees.js';
+import { dispatchViaAcp } from './acp-dispatch.js';
+import { dispatchViaPty } from './pty-dispatch.js';
 
 interface InferenceRunner {
   enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => void;
@@ -50,7 +53,29 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
 
   async function runTask(task: { id: string; project_id: string; input: string; agent: string | null; model: string | null }): Promise<void> {
     const taskId = task.id;
-    log.info({ taskId }, 'dispatcher: starting task');
+
+    // Determine execution path: if agent is specified AND exists in available_agents → Path B
+    if (task.agent) {
+      const [agentRow] = await sql<{ name: string; supports_acp: boolean }[]>`
+        SELECT name, supports_acp FROM available_agents WHERE name = ${task.agent}
+      `;
+      if (agentRow) {
+        await runExternalAgent(task, agentRow.supports_acp);
+        return;
+      }
+      // Agent specified but not available — fall through to Path A with a warning
+      log.warn({ taskId, agent: task.agent }, 'dispatcher: specified agent not available, falling back to native');
+    }
+
+    // Path A — native inference (existing behavior)
+    await runNativeInference(task);
+  }
+
+  // ─── Path A: Native Inference ───────────────────────────────────────────────
+
+  async function runNativeInference(task: { id: string; project_id: string; input: string; agent: string | null; model: string | null }): Promise<void> {
+    const taskId = task.id;
+    log.info({ taskId }, 'dispatcher: starting task (path A — native)');
 
     try {
       // Mark running
@@ -101,7 +126,6 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
       const finalStatus = await waitForCompletion(assistantId);
 
       if (stopping) {
-        // Graceful shutdown — mark cancelled
         await sql`
           UPDATE tasks
           SET state = 'cancelled', ended_at = clock_timestamp()
@@ -111,7 +135,6 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
       }
 
       if (finalStatus === 'complete') {
-        // Grab assistant content for output_summary
         const [msg] = await sql<{ content: string | null }[]>`
           SELECT content FROM messages WHERE id = ${assistantId}
         `;
@@ -121,9 +144,8 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
           SET state = 'completed', ended_at = clock_timestamp(), output_summary = ${summary}
           WHERE id = ${taskId}
         `;
-        log.info({ taskId }, 'dispatcher: task completed');
+        log.info({ taskId }, 'dispatcher: task completed (native)');
       } else {
-        // failed or cancelled
         const [msg] = await sql<{ content: string | null }[]>`
           SELECT content FROM messages WHERE id = ${assistantId}
         `;
@@ -133,21 +155,176 @@ export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<v
           SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${summary}
           WHERE id = ${taskId}
         `;
-        log.warn({ taskId, finalStatus }, 'dispatcher: task failed');
+        log.warn({ taskId, finalStatus }, 'dispatcher: task failed (native)');
       }
     } catch (err) {
       const errMsg = err instanceof Error ? err.message : String(err);
-      log.error({ taskId, err: errMsg }, 'dispatcher: task error');
+      log.error({ taskId, err: errMsg }, 'dispatcher: task error (native)');
       await sql`
         UPDATE tasks
         SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${errMsg.slice(0, 500)}
         WHERE id = ${taskId}
-      `.catch(() => {}); // best-effort
+      `.catch(() => {});
     }
   }
 
+  // ─── Path B: External Agent Dispatch ──────<E29480><E29480><EFBFBD>─────────────────────────────────
+
+  async function runExternalAgent(
+    task: { id: string; project_id: string; input: string; agent: string | null; model: string | null },
+    supportsAcp: boolean,
+  ): Promise<void> {
+    const taskId = task.id;
+    const agent = task.agent!;
+    const executionPath = supportsAcp ? 'acp' : 'pty';
+
+    log.info({ taskId, agent, executionPath }, 'dispatcher: starting task (path B — external)');
+
+    // Resolve the project's root path
+    const [project] = await sql<{ root_path: string | null }[]>`
+      SELECT root_path FROM projects WHERE id = ${task.project_id}
+    `;
+    const projectPath = project?.root_path;
+    if (!projectPath) {
+      await sql`
+        UPDATE tasks
+        SET state = 'failed', ended_at = clock_timestamp(), output_summary = 'Project has no root_path — cannot create worktree'
+        WHERE id = ${taskId}
+      `;
+      return;
+    }
+
+    // Create an abort controller for this task
+    const ac = new AbortController();
+
+    try {
+      // Mark running
+      await sql`
+        UPDATE tasks
+        SET state = 'running', started_at = clock_timestamp(), execution_path = ${executionPath}
+        WHERE id = ${taskId}
+      `;
+
+      // Create session + chat for this task (same as Path A — for output tracking)
+      const sessionName = `Task [${agent}]: ${task.input.slice(0, 30)}`;
+      const [session] = await sql<{ id: string }[]>`
+        INSERT INTO sessions (project_id, name, model, status)
+        VALUES (${task.project_id}, ${sessionName}, ${task.model ?? config.DEFAULT_MODEL}, 'open')
+        RETURNING id
+      `;
+      const sessionId = session!.id;
+
+      const [chat] = await sql<{ id: string }[]>`
+        INSERT INTO chats (session_id, name, status)
+        VALUES (${sessionId}, 'External agent execution', 'open')
+        RETURNING id
+      `;
+      const chatId = chat!.id;
+
+      // Link task to session
+      await sql`UPDATE tasks SET session_id = ${sessionId} WHERE id = ${taskId}`;
+
+      // Create user message for the task input
+      await sql`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'user', ${task.input}, 'complete', clock_timestamp())
+      `;
+
+      // Step 1: Create worktree
+      log.info({ taskId, projectPath }, 'dispatcher: creating worktree');
+      const worktreePath = await createWorktree(projectPath, taskId, { signal: ac.signal });
+      log.info({ taskId, worktreePath }, 'dispatcher: worktree created');
+
+      // Step 2: Dispatch to agent
+      let outputSummary: string;
+
+      if (supportsAcp) {
+        const result = await dispatchViaAcp({
+          agent,
+          task: task.input,
+          worktreePath,
+          model: task.model ?? undefined,
+          signal: ac.signal,
+          log,
+        });
+        outputSummary = result.output.slice(0, 500);
+
+        // Store agent output as an assistant message
+        await sql`
+          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+          VALUES (${sessionId}, ${chatId}, 'assistant', ${result.output.slice(0, 50_000)}, 'complete', clock_timestamp())
+        `;
+      } else {
+        const result = await dispatchViaPty({
+          agent,
+          task: task.input,
+          worktreePath,
+          model: task.model ?? undefined,
+          signal: ac.signal,
+          log,
+        });
+        outputSummary = (result.stdout || result.stderr).slice(0, 500);
+
+        // Store agent output as an assistant message
+        const content = result.stdout || result.stderr || '(no output)';
+        await sql`
+          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+          VALUES (${sessionId}, ${chatId}, 'assistant', ${content.slice(0, 50_000)}, 'complete', clock_timestamp())
+        `;
+      }
+
+      if (stopping) {
+        await sql`
+          UPDATE tasks SET state = 'cancelled', ended_at = clock_timestamp() WHERE id = ${taskId}
+        `;
+        await cleanupWorktree(projectPath, taskId);
+        return;
+      }
+
+      // Step 3: Diff the worktree and queue pending changes
+      log.info({ taskId }, 'dispatcher: diffing worktree');
+      const diff = await diffWorktree(worktreePath, projectPath, { signal: ac.signal });
+
+      if (diff) {
+        // Queue a single pending_change entry with the full unified diff
+        await sql`
+          INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
+          VALUES (${sessionId}, ${taskId}, ${projectPath}, 'edit', ${diff})
+        `;
+        log.info({ taskId, diffLength: diff.length }, 'dispatcher: diff queued as pending change');
+      } else {
+        log.info({ taskId }, 'dispatcher: no changes detected in worktree');
+      }
+
+      // Step 4: Cleanup worktree
+      await cleanupWorktree(projectPath, taskId);
+
+      // Step 5: Mark task completed
+      await sql`
+        UPDATE tasks
+        SET state = 'completed', ended_at = clock_timestamp(), output_summary = ${outputSummary}
+        WHERE id = ${taskId}
+      `;
+      log.info({ taskId, agent }, 'dispatcher: task completed (external)');
+
+    } catch (err) {
+      const errMsg = err instanceof Error ? err.message : String(err);
+      log.error({ taskId, agent, err: errMsg }, 'dispatcher: external agent error');
+
+      await sql`
+        UPDATE tasks
+        SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${errMsg.slice(0, 500)}
+        WHERE id = ${taskId}
+      `.catch(() => {});
+
+      // Best-effort cleanup
+      await cleanupWorktree(projectPath, taskId);
+    }
+  }
+
+  // ─── Helpers ────────────────────────────────────────────────────────────────
+
   async function waitForCompletion(assistantId: string): Promise<string> {
-    // Poll until the assistant message is no longer streaming
     for (;;) {
       if (stopping) return 'cancelled';
 

apps/coder/src/services/pty-dispatch.ts

@@ -0,0 +1,139 @@
+/**
+ * PTY dispatch — runs external agents on the host via SSH.
+ *
+ * For agents without ACP support (claude, pi), we pipe the task into their
+ * non-interactive mode and capture stdout/stderr. The agent runs in a git
+ * worktree so it can modify files freely.
+ *
+ * Supported agents:
+ * - claude: `claude -p --model <model>` (print mode, reads task from stdin)
+ * - opencode: `echo <task> | opencode` (stdin pipe — exact flags TBD)
+ * - goose: stub (not yet supported)
+ * - pi: stub (not yet supported)
+ */
+import type { FastifyBaseLogger } from 'fastify';
+import { sshSpawnWithStdin } from './ssh.js';
+
+export interface DispatchResult {
+  exitCode: number;
+  stdout: string;
+  stderr: string;
+}
+
+export interface PtyDispatchOpts {
+  agent: string;
+  task: string;
+  worktreePath: string;
+  model?: string;
+  signal?: AbortSignal;
+  log: FastifyBaseLogger;
+}
+
+/**
+ * Build the shell command that runs the agent non-interactively.
+ * The command will be executed inside `cd <worktreePath> && ...`.
+ */
+function buildAgentCommand(agent: string, task: string, model?: string): string | null {
+  // Escape the task for embedding in a shell command
+  const escapedTask = task.replace(/'/g, "'\\''");
+
+  switch (agent) {
+    case 'claude':
+      // Claude Code's print mode: reads prompt from stdin, runs autonomously, prints result
+      return model
+        ? `echo '${escapedTask}' | claude -p --model '${model}'`
+        : `echo '${escapedTask}' | claude -p`;
+
+    case 'opencode':
+      // opencode non-interactive: pipe task via stdin
+      // NOTE: exact flags may vary — opencode may need --non-interactive or --pipe
+      return model
+        ? `echo '${escapedTask}' | opencode --model '${model}'`
+        : `echo '${escapedTask}' | opencode`;
+
+    case 'goose':
+      // Not yet verified for non-interactive use
+      return null;
+
+    case 'pi':
+      // Not yet verified for non-interactive use
+      return null;
+
+    default:
+      return null;
+  }
+}
+
+/**
+ * Dispatch a task to an external agent via SSH.
+ *
+ * The agent runs in the worktree directory on the host. stdout/stderr are
+ * captured in full and returned. The SSH process is killed on abort signal.
+ */
+export async function dispatchViaPty(opts: PtyDispatchOpts): Promise<DispatchResult> {
+  const { agent, task, worktreePath, model, signal, log } = opts;
+
+  const agentCmd = buildAgentCommand(agent, task, model);
+  if (!agentCmd) {
+    return {
+      exitCode: 1,
+      stdout: '',
+      stderr: `Agent '${agent}' is not yet supported for PTY dispatch.`,
+    };
+  }
+
+  // Wrap in cd to the worktree
+  const fullCommand = `cd '${worktreePath.replace(/'/g, "'\\''")}' && ${agentCmd}`;
+
+  log.info({ agent, worktreePath }, 'pty-dispatch: starting');
+
+  return new Promise<DispatchResult>((resolve, reject) => {
+    const child = sshSpawnWithStdin(fullCommand, '');
+    // Note: sshSpawnWithStdin already closes stdin. For agents that read from
+    // stdin via echo piping, the command itself handles the piping on the remote
+    // side. We just need the SSH tunnel.
+
+    // Actually, re-think: sshSpawnWithStdin writes input and closes stdin on the
+    // LOCAL ssh process. But the remote command is `echo '...' | agent`, which
+    // provides its own stdin. So we should use sshSpawn (no local stdin needed)
+    // or just let the empty stdin close — the remote shell handles piping internally.
+    // This is fine as-is because the echo piping happens WITHIN the remote shell command.
+
+    let stdout = '';
+    let stderr = '';
+    let killed = false;
+
+    child.stdout!.on('data', (chunk: Buffer) => { stdout += chunk.toString(); });
+    child.stderr!.on('data', (chunk: Buffer) => { stderr += chunk.toString(); });
+
+    const cleanup = () => {
+      if (!killed) {
+        killed = true;
+        child.kill('SIGTERM');
+        // Give it a moment then force-kill
+        setTimeout(() => child.kill('SIGKILL'), 5_000);
+      }
+    };
+
+    if (signal) {
+      if (signal.aborted) {
+        cleanup();
+        resolve({ exitCode: 130, stdout: '', stderr: 'Aborted before start' });
+        return;
+      }
+      signal.addEventListener('abort', cleanup, { once: true });
+    }
+
+    child.on('close', (code) => {
+      if (signal) signal.removeEventListener('abort', cleanup);
+      log.info({ agent, exitCode: code }, 'pty-dispatch: completed');
+      resolve({ exitCode: code ?? 1, stdout, stderr });
+    });
+
+    child.on('error', (err) => {
+      if (signal) signal.removeEventListener('abort', cleanup);
+      log.error({ agent, err: err.message }, 'pty-dispatch: spawn error');
+      reject(err);
+    });
+  });
+}

apps/coder/src/services/ssh.ts

@@ -0,0 +1,126 @@
+/**
+ * SSH helper — spawns commands on the host via SSH.
+ *
+ * BooCode's container cannot directly spawn host processes (opencode, goose, claude, pi).
+ * They live on the HOST at /usr/local/bin/ or Sam's PATH. We SSH to the host over the
+ * Tailscale IP (same mechanism BooTerm uses: samkintop@100.114.205.53).
+ */
+import { spawn, type ChildProcess } from 'node:child_process';
+
+export const SSH_HOST = process.env.BOOCODER_SSH_HOST ?? '100.114.205.53';
+export const SSH_USER = process.env.BOOCODER_SSH_USER ?? 'samkintop';
+
+/** Common SSH args — strict host checking disabled for container-to-host trust. */
+const SSH_BASE_ARGS = [
+  '-o', 'StrictHostKeyChecking=no',
+  '-o', 'UserKnownHostsFile=/dev/null',
+  '-o', 'LogLevel=ERROR',
+  '-o', 'BatchMode=yes',
+];
+
+export interface SshExecResult {
+  exitCode: number;
+  stdout: string;
+  stderr: string;
+}
+
+/**
+ * Execute a command on the host via SSH, collecting all output.
+ * Returns when the remote process exits.
+ */
+export async function sshExec(
+  command: string,
+  opts?: { signal?: AbortSignal; timeoutMs?: number },
+): Promise<SshExecResult> {
+  return new Promise<SshExecResult>((resolve, reject) => {
+    const child = spawn('ssh', [
+      ...SSH_BASE_ARGS,
+      `${SSH_USER}@${SSH_HOST}`,
+      command,
+    ], {
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+
+    let stdout = '';
+    let stderr = '';
+    let killed = false;
+
+    child.stdout!.on('data', (chunk: Buffer) => { stdout += chunk.toString(); });
+    child.stderr!.on('data', (chunk: Buffer) => { stderr += chunk.toString(); });
+
+    const cleanup = () => {
+      if (!killed) {
+        killed = true;
+        child.kill('SIGTERM');
+      }
+    };
+
+    // Abort signal
+    if (opts?.signal) {
+      if (opts.signal.aborted) {
+        cleanup();
+        reject(new Error('SSH exec aborted before start'));
+        return;
+      }
+      opts.signal.addEventListener('abort', cleanup, { once: true });
+    }
+
+    // Timeout
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    if (opts?.timeoutMs) {
+      timer = setTimeout(() => {
+        cleanup();
+        reject(new Error(`SSH exec timed out after ${opts.timeoutMs}ms`));
+      }, opts.timeoutMs);
+    }
+
+    child.on('close', (code) => {
+      if (timer) clearTimeout(timer);
+      if (opts?.signal) opts.signal.removeEventListener('abort', cleanup);
+      resolve({ exitCode: code ?? 1, stdout, stderr });
+    });
+
+    child.on('error', (err) => {
+      if (timer) clearTimeout(timer);
+      if (opts?.signal) opts.signal.removeEventListener('abort', cleanup);
+      reject(err);
+    });
+
+    // Close stdin immediately — we're not sending input via sshExec
+    child.stdin!.end();
+  });
+}
+
+/**
+ * Spawn an SSH child process with a command on the host.
+ * Returns the raw ChildProcess for callers that need streaming I/O (ACP, PTY).
+ */
+export function sshSpawn(command: string): ChildProcess {
+  return spawn('ssh', [
+    ...SSH_BASE_ARGS,
+    `${SSH_USER}@${SSH_HOST}`,
+    command,
+  ], {
+    stdio: ['pipe', 'pipe', 'pipe'],
+  });
+}
+
+/**
+ * Spawn an SSH child process that pipes stdin through.
+ * Used for agents that read a task from stdin (e.g. `echo "task" | claude -p`).
+ */
+export function sshSpawnWithStdin(command: string, input: string): ChildProcess {
+  const child = spawn('ssh', [
+    ...SSH_BASE_ARGS,
+    `${SSH_USER}@${SSH_HOST}`,
+    command,
+  ], {
+    stdio: ['pipe', 'pipe', 'pipe'],
+  });
+
+  // Write the input and close stdin
+  child.stdin!.write(input);
+  child.stdin!.end();
+
+  return child;
+}

apps/coder/src/services/worktrees.ts

@@ -0,0 +1,118 @@
+/**
+ * Git worktree management for external agent dispatch.
+ *
+ * Each dispatched task gets its own git worktree so the external agent
+ * can modify files freely without touching the main working tree.
+ * After the agent completes, we diff the worktree against HEAD and
+ * queue the diff into pending_changes.
+ */
+import { sshExec } from './ssh.js';
+
+const WORKTREE_BASE = '/tmp/booworktrees';
+
+/**
+ * Create a git worktree for a task on the host.
+ * Returns the absolute path to the worktree directory.
+ */
+export async function createWorktree(
+  projectPath: string,
+  taskId: string,
+  opts?: { signal?: AbortSignal },
+): Promise<string> {
+  const worktreePath = `${WORKTREE_BASE}/${taskId}`;
+  const branchName = `task-${taskId}`;
+
+  // Ensure the base directory exists
+  await sshExec(`mkdir -p ${WORKTREE_BASE}`, { signal: opts?.signal });
+
+  // Create the worktree with a new branch from HEAD
+  const result = await sshExec(
+    `git -C ${shellEscape(projectPath)} worktree add ${shellEscape(worktreePath)} -b ${shellEscape(branchName)} HEAD`,
+    { signal: opts?.signal, timeoutMs: 30_000 },
+  );
+
+  if (result.exitCode !== 0) {
+    throw new Error(`Failed to create worktree: ${result.stderr.trim() || result.stdout.trim()}`);
+  }
+
+  return worktreePath;
+}
+
+/**
+ * Get the unified diff of changes made in the worktree vs the parent branch (HEAD).
+ * Returns an empty string if there are no changes.
+ */
+export async function diffWorktree(
+  worktreePath: string,
+  projectPath: string,
+  opts?: { signal?: AbortSignal },
+): Promise<string> {
+  // First, commit any uncommitted changes in the worktree so we can diff branches
+  // Stage all changes
+  const addResult = await sshExec(
+    `cd ${shellEscape(worktreePath)} && git add -A`,
+    { signal: opts?.signal, timeoutMs: 30_000 },
+  );
+  if (addResult.exitCode !== 0) {
+    throw new Error(`Failed to stage worktree changes: ${addResult.stderr.trim()}`);
+  }
+
+  // Check if there are staged changes
+  const statusResult = await sshExec(
+    `cd ${shellEscape(worktreePath)} && git diff --cached --quiet`,
+    { signal: opts?.signal, timeoutMs: 10_000 },
+  );
+
+  if (statusResult.exitCode === 0) {
+    // No changes
+    return '';
+  }
+
+  // Commit staged changes (needed to produce a clean branch diff)
+  await sshExec(
+    `cd ${shellEscape(worktreePath)} && git -c user.email=boocoder@local -c user.name=BooCoder commit -m "task changes" --allow-empty`,
+    { signal: opts?.signal, timeoutMs: 15_000 },
+  );
+
+  // Diff the worktree branch against the parent commit (HEAD of main tree)
+  const diffResult = await sshExec(
+    `git -C ${shellEscape(projectPath)} diff HEAD...$(git -C ${shellEscape(worktreePath)} rev-parse HEAD)`,
+    { signal: opts?.signal, timeoutMs: 60_000 },
+  );
+
+  if (diffResult.exitCode !== 0) {
+    throw new Error(`Failed to diff worktree: ${diffResult.stderr.trim()}`);
+  }
+
+  return diffResult.stdout;
+}
+
+/**
+ * Remove a worktree and its associated branch.
+ * Best-effort — does not throw on failure (task may have already been cleaned up).
+ */
+export async function cleanupWorktree(
+  projectPath: string,
+  taskId: string,
+): Promise<void> {
+  const worktreePath = `${WORKTREE_BASE}/${taskId}`;
+  const branchName = `task-${taskId}`;
+
+  // Remove the worktree (--force handles dirty state)
+  await sshExec(
+    `git -C ${shellEscape(projectPath)} worktree remove ${shellEscape(worktreePath)} --force`,
+    { timeoutMs: 15_000 },
+  ).catch(() => {});
+
+  // Delete the task branch
+  await sshExec(
+    `git -C ${shellEscape(projectPath)} branch -D ${shellEscape(branchName)}`,
+    { timeoutMs: 10_000 },
+  ).catch(() => {});
+}
+
+/** Minimal shell escape for paths (single-quote wrapping). */
+function shellEscape(s: string): string {
+  // Replace single quotes with escaped version, wrap in single quotes
+  return "'" + s.replace(/'/g, "'\\''") + "'";
+}

pnpm-lock.yaml

@@ -48,6 +48,9 @@ importers:
 
   apps/coder:
     dependencies:
+      '@agentclientprotocol/sdk':
+        specifier: ^0.22.1
+        version: 0.22.1(zod@3.25.76)
       '@boocode/server':
         specifier: workspace:*
         version: link:../server
@@ -268,6 +271,11 @@ importers:
 
 packages:
 
+  '@agentclientprotocol/sdk@0.22.1':
+    resolution: {integrity: sha512-DfqXtl/8gO9NImq094MTaCXEU2vkhh6v7q/kT+9UjZxUqj8hYaya2OjLVIqn16MzNHcXEpShTR2RIauLSYeDQQ==}
+    peerDependencies:
+      zod: ^3.25.0 || ^4.0.0
+
   '@ai-sdk/gateway@3.0.119':
     resolution: {integrity: sha512-VAhfRWC+JexZakkVfmjaJKaTj00x7/UHdE8kMWL3NhuQAlf8oXtg9r4dfvFZrByXxchGRBvYE3biEUyibkg0xg==}
     engines: {node: '>=18'}
@@ -4097,6 +4105,10 @@ packages:
 
 snapshots:
 
+  '@agentclientprotocol/sdk@0.22.1(zod@3.25.76)':
+    dependencies:
+      zod: 3.25.76
+
   '@ai-sdk/gateway@3.0.119(zod@3.25.76)':
     dependencies:
       '@ai-sdk/provider': 3.0.10