feat(cli): resume completed threads (衔尾蛇: end → start)

uwf thread resume now supports completed threads:
- Evaluates workflow graph from $START to find first role
- Clears completed state (status → idle, completedAt → null)
- Builds resume prompt with supplement context
- Full CAS chain preserved for rich context

Suspended resume behavior unchanged.
Cancelled/idle threads still rejected.

425 tests pass.

Part of #39, closes #43

packages/cli/src/__tests__/thread-resume.test.ts

@@ -249,7 +249,7 @@ describe("uwf thread resume", () => {
 
     const result = runUwf(["thread", "resume", THREAD_ID], casDir);
     expect(result.status).not.toBe(0);
-    expect(result.stderr).toContain("thread is not suspended");
+    expect(result.stderr).toContain("thread cannot be resumed");
   });
 
   test("resume suspended thread executes step and becomes idle", async () => {
@@ -448,3 +448,266 @@ echo '${adapterJson}'
 
   return { mockAgentPath };
 }
+
+describe("uwf thread resume - completed threads", () => {
+  test("resume completed thread starts from $START role", async () => {
+    const casDir = join(tmpDir, "cas");
+    await mkdir(casDir, { recursive: true });
+    const store = await openStore(casDir);
+    const schemas = await registerUwfSchemas(store);
+    const outputSchemaHash = await putSchema(store, OUTPUT_SCHEMA);
+
+    const workflowHash = await store.cas.put(schemas.workflow, {
+      name: "test-completed-resume",
+      description: "completed thread resume test",
+      roles: {
+        worker: {
+          description: "Worker role",
+          goal: "Work",
+          capabilities: [],
+          procedure: "work",
+          output: "result",
+          frontmatter: outputSchemaHash,
+        },
+        reviewer: {
+          description: "Reviewer role",
+          goal: "Review",
+          capabilities: [],
+          procedure: "review",
+          output: "result",
+          frontmatter: outputSchemaHash,
+        },
+      },
+      graph: {
+        $START: { _: { role: "worker", prompt: "Start work", location: null } },
+        worker: { _: { role: "reviewer", prompt: "Review the work", location: null } },
+        reviewer: { _: { role: "$END", prompt: "Done", location: null } },
+      },
+    });
+
+    const startHash = await store.cas.put(schemas.startNode, {
+      workflow: workflowHash,
+      prompt: "Initial task",
+      cwd: tmpDir,
+    });
+
+    process.env.OCAS_DIR = casDir;
+
+    const workerOutputHash = await store.cas.put(outputSchemaHash, { $status: "_" });
+    const reviewerOutputHash = await store.cas.put(outputSchemaHash, { $status: "_" });
+    const detailHash = await store.cas.put(schemas.text, "mock detail");
+
+    const workerStepHash = await store.cas.put(schemas.stepNode, {
+      start: startHash,
+      prev: null,
+      role: "worker",
+      output: workerOutputHash,
+      detail: detailHash,
+      agent: "uwf-mock",
+      edgePrompt: "Start work",
+      startedAtMs: 1716600000000,
+      completedAtMs: 1716600001000,
+      cwd: tmpDir,
+      assembledPrompt: null,
+    });
+
+    const reviewerStepHash = await store.cas.put(schemas.stepNode, {
+      start: startHash,
+      prev: workerStepHash,
+      role: "reviewer",
+      output: reviewerOutputHash,
+      detail: detailHash,
+      agent: "uwf-mock",
+      edgePrompt: "Review the work",
+      startedAtMs: 1716600001000,
+      completedAtMs: 1716600002000,
+      cwd: tmpDir,
+      assembledPrompt: null,
+    });
+
+    await seedThreads(tmpDir, {
+      [THREAD_ID]: {
+        head: reviewerStepHash,
+        status: "completed",
+        suspendedRole: null,
+        suspendMessage: null,
+        completedAt: 1716600002000,
+      },
+    });
+
+    // Verify the status was actually set
+    const { createUwfStore, getThread } = await import("../store.js");
+    const verifyUwf = await createUwfStore(tmpDir);
+    const verifyEntry = getThread(verifyUwf.varStore, THREAD_ID);
+    // biome-ignore lint/nursery/noConsole: test debugging
+    console.log("Seeded entry status:", verifyEntry?.status);
+    // biome-ignore lint/nursery/noConsole: test debugging
+    console.log("Seeded entry:", JSON.stringify(verifyEntry, null, 2));
+
+    const promptCapturePath = join(tmpDir, "captured-prompt-completed.txt");
+    const mockAgentPath = join(tmpDir, "mock-agent-completed.sh");
+
+    const newWorkerStepHash = await store.cas.put(schemas.stepNode, {
+      start: startHash,
+      prev: reviewerStepHash,
+      role: "worker",
+      output: workerOutputHash,
+      detail: detailHash,
+      agent: "uwf-mock",
+      edgePrompt: "Start work",
+      startedAtMs: 1716600003000,
+      completedAtMs: 1716600004000,
+      cwd: tmpDir,
+      assembledPrompt: null,
+    });
+
+    const adapterJson = JSON.stringify({
+      stepHash: newWorkerStepHash,
+      detailHash,
+      role: "worker",
+      frontmatter: { $status: "_" },
+      body: "",
+      startedAtMs: 1716600003000,
+      completedAtMs: 1716600004000,
+    });
+
+    await writeFile(
+      mockAgentPath,
+      `#!/bin/sh
+prompt=""
+while [ $# -gt 0 ]; do
+  if [ "$1" = "--prompt" ]; then
+    prompt="$2"
+    shift 2
+  else
+    shift
+  fi
+done
+printf '%s' "$prompt" > '${promptCapturePath}'
+echo '${adapterJson}'
+`,
+      { mode: 0o755 },
+    );
+
+    const configPath = join(tmpDir, "config.yaml");
+    await writeFile(
+      configPath,
+      `defaultAgent: uwf-hermes\ndefaultModel: test-model\nagentOverrides: null\nagents: {}\nproviders: {}\nmodels: {}\n`,
+    );
+
+    const result = runUwf(
+      ["thread", "resume", THREAD_ID, "-p", "Additional context", "--agent", mockAgentPath],
+      casDir,
+    );
+
+    if (result.status !== 0) {
+      // biome-ignore lint/nursery/noConsole: test debugging
+      console.error("Command failed:", result.stderr);
+    }
+
+    expect(result.status).toBe(0);
+
+    const cliOutput = JSON.parse(result.stdout.trim());
+    expect(cliOutput.status).toBe("idle");
+    expect(cliOutput.currentRole).toBe("reviewer");
+    expect(cliOutput.done).toBe(false);
+
+    const capturedPrompt = await readFile(promptCapturePath, "utf8");
+    expect(capturedPrompt).toContain("Previous run completed");
+    expect(capturedPrompt).toContain("Additional context");
+
+    const storeModule = await import("../store.js");
+    const uwf2 = await storeModule.createUwfStore(tmpDir);
+    const entry2 = storeModule.getThread(uwf2.varStore, THREAD_ID);
+    expect(entry2?.status).toBe("idle");
+    expect(entry2?.completedAt).toBeNull();
+  });
+
+  test("resume cancelled thread returns error", async () => {
+    const casDir = join(tmpDir, "cas");
+    await mkdir(casDir, { recursive: true });
+    const store = await openStore(casDir);
+    const schemas = await registerUwfSchemas(store);
+
+    const workflowHash = await store.cas.put(schemas.workflow, {
+      name: "cancelled-workflow",
+      description: "cancelled thread",
+      roles: {
+        worker: {
+          description: "Worker",
+          goal: "Work",
+          capabilities: [],
+          procedure: "work",
+          output: "result",
+          frontmatter: await putSchema(store, OUTPUT_SCHEMA),
+        },
+      },
+      graph: {
+        $START: { _: { role: "worker", prompt: "Start", location: null } },
+        worker: { _: { role: "$END", prompt: "Done", location: null } },
+      },
+    });
+
+    const startHash = await store.cas.put(schemas.startNode, {
+      workflow: workflowHash,
+      prompt: "task",
+      cwd: tmpDir,
+    });
+
+    process.env.OCAS_DIR = casDir;
+    await seedThreads(tmpDir, {
+      [THREAD_ID]: {
+        head: startHash,
+        status: "cancelled",
+        suspendedRole: null,
+        suspendMessage: null,
+        completedAt: null,
+      },
+    });
+
+    const result = runUwf(["thread", "resume", THREAD_ID], casDir);
+    expect(result.status).not.toBe(0);
+    expect(result.stderr).toContain("thread cannot be resumed");
+    expect(result.stderr).toContain("cancelled");
+  });
+
+  test("resume idle thread returns error", async () => {
+    const casDir = join(tmpDir, "cas");
+    await mkdir(casDir, { recursive: true });
+    const store = await openStore(casDir);
+    const schemas = await registerUwfSchemas(store);
+
+    const workflowHash = await store.cas.put(schemas.workflow, {
+      name: "idle-workflow",
+      description: "idle thread",
+      roles: {
+        worker: {
+          description: "Worker",
+          goal: "Work",
+          capabilities: [],
+          procedure: "work",
+          output: "result",
+          frontmatter: await putSchema(store, OUTPUT_SCHEMA),
+        },
+      },
+      graph: {
+        $START: { _: { role: "worker", prompt: "Start", location: null } },
+        worker: { _: { role: "$END", prompt: "Done", location: null } },
+      },
+    });
+
+    const startHash = await store.cas.put(schemas.startNode, {
+      workflow: workflowHash,
+      prompt: "task",
+      cwd: tmpDir,
+    });
+
+    process.env.OCAS_DIR = casDir;
+    await seedThreads(tmpDir, { [THREAD_ID]: startHash });
+
+    const result = runUwf(["thread", "resume", THREAD_ID], casDir);
+    expect(result.status).not.toBe(0);
+    expect(result.stderr).toContain("thread cannot be resumed");
+    expect(result.stderr).toContain("idle");
+  });
+});

packages/cli/src/commands/thread.ts

@@ -1051,40 +1051,84 @@ export async function cmdThreadResume(
   const chain = walkChain(uwf, headHash);
   const workflowHash = chain.start.workflow;
 
-  const status = await resolveActiveThreadStatus(
-    storageRoot,
-    threadId,
-    uwf,
-    headHash,
-    workflowHash,
-  );
-  if (status !== "suspended") {
-    fail(`thread is not suspended: ${threadId} (status: ${status})`);
+  // Check entry.status first for completed/cancelled (like in cmdThreadShow)
+  let status: ThreadStatus;
+  if (entry.status === "completed" || entry.status === "cancelled") {
+    status = entry.status;
+  } else {
+    status = await resolveActiveThreadStatus(
+      storageRoot,
+      threadId,
+      uwf,
+      headHash,
+      workflowHash,
+    );
   }
 
-  const suspendFields = resolveSuspendFieldsForShow(entry, status, uwf, headHash, workflowHash);
-  if (suspendFields.suspendedRole === null) {
-    fail(`thread is suspended but suspendedRole is missing: ${threadId}`);
-  }
-  if (suspendFields.suspendMessage === null) {
-    fail(`thread is suspended but suspendMessage is missing: ${threadId}`);
+  if (status !== "suspended" && status !== "completed") {
+    fail(`thread cannot be resumed: ${threadId} (status: ${status})`);
   }
 
-  const resumePrompt = buildResumePrompt(suspendFields.suspendMessage, supplement);
   const plog = createProcessLogger({
     storageRoot,
     context: { thread: threadId, workflow: workflowHash },
   });
 
+  if (status === "suspended") {
+    const suspendFields = resolveSuspendFieldsForShow(entry, status, uwf, headHash, workflowHash);
+    if (suspendFields.suspendedRole === null) {
+      fail(`thread is suspended but suspendedRole is missing: ${threadId}`);
+    }
+    if (suspendFields.suspendMessage === null) {
+      fail(`thread is suspended but suspendMessage is missing: ${threadId}`);
+    }
+
+    const resumePrompt = buildResumePrompt(suspendFields.suspendMessage, supplement);
+
+    plog.log(
+      PL_THREAD_RESUME,
+      `resume role=${suspendFields.suspendedRole} supplement=${supplement !== null}`,
+      null,
+    );
+
+    return cmdThreadStepOnce(storageRoot, threadId, agentOverride, plog, {
+      role: suspendFields.suspendedRole,
+      prompt: resumePrompt,
+    });
+  }
+
+  // status === "completed"
+  const workflow = loadWorkflowPayload(uwf, workflowHash);
+  const startResult = evaluate(workflow.graph, START_ROLE, {});
+  if (!startResult.ok) {
+    fail(`failed to evaluate $START: ${startResult.error.message}`);
+  }
+  if (isSuspendResult(startResult.value)) {
+    fail("workflow cannot start with $SUSPEND");
+  }
+  if (startResult.value.role === END_ROLE) {
+    fail("workflow cannot start with $END");
+  }
+
+  const startRole = startResult.value.role;
+  const completedPromptPrefix = "Previous run completed. Resuming with additional context.";
+  const completedResumePrompt =
+    supplement !== null && supplement !== ""
+      ? `${completedPromptPrefix}\n\n${supplement}`
+      : completedPromptPrefix;
+
+  const updatedEntry = { ...entry, status: "idle" as const, completedAt: null };
+  setThread(uwf.varStore, threadId, updatedEntry);
+
   plog.log(
     PL_THREAD_RESUME,
-    `resume role=${suspendFields.suspendedRole} supplement=${supplement !== null}`,
+    `resume completed role=${startRole} supplement=${supplement !== null}`,
     null,
   );
 
   return cmdThreadStepOnce(storageRoot, threadId, agentOverride, plog, {
-    role: suspendFields.suspendedRole,
-    prompt: resumePrompt,
+    role: startRole,
+    prompt: completedResumePrompt,
   });
 }