feat: extract session cache to agent-kit, add resume to claude-code agent

Move getCachedSessionId/setCachedSessionId from workflow-agent-hermes
into workflow-agent-kit so all agent adapters can share the same
session cache logic.

Add cross-process session resume to workflow-agent-claude-code:
on re-entry (isFirstVisit=false), look up the cached sessionId and
use 'claude --resume' to continue with full conversation history.

Cache file renamed from hermes-sessions.json to agent-sessions.json
to reflect its shared nature.

Refs #418

packages/workflow-agent-claude-code/src/claude-code.ts

@@ -6,6 +6,8 @@ import {
   type AgentRunResult,
   buildRolePrompt,
   createAgent,
+  getCachedSessionId,
+  setCachedSessionId,
 } from "@uncaged/workflow-agent-kit";
 
 import { parseClaudeCodeJsonOutput, storeClaudeCodeDetail } from "./session-detail.js";
@@ -125,8 +127,26 @@ async function processClaudeOutput(stdout: string, store: Store): Promise<AgentR
 
 async function runClaudeCode(ctx: AgentContext): Promise<AgentRunResult> {
   const fullPrompt = buildClaudeCodePrompt(ctx);
+
+  // Try resuming a cached session for re-entry scenarios (e.g. reviewer reject → developer re-entry).
+  if (!ctx.isFirstVisit) {
+    const cachedSessionId = await getCachedSessionId(ctx.threadId, ctx.role);
+    if (cachedSessionId !== null) {
+      try {
+        const { stdout } = await spawnClaudeResume(cachedSessionId, fullPrompt);
+        const result = await processClaudeOutput(stdout, ctx.store);
+        await setCachedSessionId(ctx.threadId, ctx.role, result.sessionId);
+        return result;
+      } catch {
+        // Resume failed — fall through to fresh run.
+      }
+    }
+  }
+
   const { stdout } = await spawnClaudeRun(fullPrompt);
-  return processClaudeOutput(stdout, ctx.store);
+  const result = await processClaudeOutput(stdout, ctx.store);
+  await setCachedSessionId(ctx.threadId, ctx.role, result.sessionId);
+  return result;
 }
 
 async function continueClaudeCode(

packages/workflow-agent-hermes/src/session-cache.ts

@@ -1,52 +1,5 @@
-import { mkdir, readFile, writeFile } from "node:fs/promises";
-import { dirname, join } from "node:path";
-
-import { resolveStorageRoot } from "@uncaged/workflow-agent-kit";
-import type { ThreadId } from "@uncaged/workflow-protocol";
-
-type HermesSessionCache = Record<string, string>;
-
-function getCachePath(): string {
-  return join(resolveStorageRoot(), "cache", "hermes-sessions.json");
-}
-
-function cacheKey(threadId: ThreadId, role: string): string {
-  return `${threadId}:${role}`;
-}
-
-function isRecord(value: unknown): value is Record<string, unknown> {
-  return typeof value === "object" && value !== null && !Array.isArray(value);
-}
-
-async function readCache(): Promise<HermesSessionCache> {
-  const path = getCachePath();
-  try {
-    const text = await readFile(path, "utf8");
-    const raw = JSON.parse(text) as unknown;
-    if (!isRecord(raw)) {
-      return {};
-    }
-    const cache: HermesSessionCache = {};
-    for (const [key, value] of Object.entries(raw)) {
-      if (typeof value === "string" && value !== "") {
-        cache[key] = value;
-      }
-    }
-    return cache;
-  } catch (e) {
-    const err = e as NodeJS.ErrnoException;
-    if (err.code === "ENOENT") {
-      return {};
-    }
-    throw e;
-  }
-}
-
-async function writeCache(cache: HermesSessionCache): Promise<void> {
-  const path = getCachePath();
-  await mkdir(dirname(path), { recursive: true });
-  await writeFile(path, `${JSON.stringify(cache, null, 2)}\n`, "utf8");
-}
+// Re-export session cache from the shared agent-kit package.
+export { getCachedSessionId, setCachedSessionId } from "@uncaged/workflow-agent-kit";
 
 export function isResumeDisabled(): boolean {
   // Hermes ACP session/resume is broken: _restore fails for custom providers
@@ -62,19 +15,3 @@ export function isResumeDisabled(): boolean {
   }
   return true;
 }
-
-export async function getCachedSessionId(threadId: ThreadId, role: string): Promise<string | null> {
-  const cache = await readCache();
-  const sessionId = cache[cacheKey(threadId, role)];
-  return sessionId ?? null;
-}
-
-export async function setCachedSessionId(
-  threadId: ThreadId,
-  role: string,
-  sessionId: string,
-): Promise<void> {
-  const cache = await readCache();
-  cache[cacheKey(threadId, role)] = sessionId;
-  await writeCache(cache);
-}

packages/workflow-agent-kit/src/index.ts

@@ -13,6 +13,7 @@ export type { FrontmatterFastPathResult } from "./frontmatter.js";
 export { tryFrontmatterFastPath } from "./frontmatter.js";
 export { createAgent } from "./run.js";
 export { getConfigPath, getEnvPath, loadWorkflowConfig, resolveStorageRoot } from "./storage.js";
+export { getCachedSessionId, setCachedSessionId } from "./session-cache.js";
 export type {
   AgentContext,
   AgentContinueFn,

packages/workflow-agent-kit/src/session-cache.ts

@@ -0,0 +1,68 @@
+import { mkdir, readFile, writeFile } from "node:fs/promises";
+import { dirname, join } from "node:path";
+
+import type { ThreadId } from "@uncaged/workflow-protocol";
+
+import { resolveStorageRoot } from "./storage.js";
+
+type SessionCache = Record<string, string>;
+
+function getCachePath(): string {
+  return join(resolveStorageRoot(), "cache", "agent-sessions.json");
+}
+
+function cacheKey(threadId: ThreadId, role: string): string {
+  return `${threadId}:${role}`;
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+async function readCache(): Promise<SessionCache> {
+  const path = getCachePath();
+  try {
+    const text = await readFile(path, "utf8");
+    const raw = JSON.parse(text) as unknown;
+    if (!isRecord(raw)) {
+      return {};
+    }
+    const cache: SessionCache = {};
+    for (const [key, value] of Object.entries(raw)) {
+      if (typeof value === "string" && value !== "") {
+        cache[key] = value;
+      }
+    }
+    return cache;
+  } catch (e) {
+    const err = e as NodeJS.ErrnoException;
+    if (err.code === "ENOENT") {
+      return {};
+    }
+    throw e;
+  }
+}
+
+async function writeCache(cache: SessionCache): Promise<void> {
+  const path = getCachePath();
+  await mkdir(dirname(path), { recursive: true });
+  await writeFile(path, `${JSON.stringify(cache, null, 2)}\n`, "utf8");
+}
+
+/** Read the cached session ID for a thread+role pair. */
+export async function getCachedSessionId(threadId: ThreadId, role: string): Promise<string | null> {
+  const cache = await readCache();
+  const sessionId = cache[cacheKey(threadId, role)];
+  return sessionId ?? null;
+}
+
+/** Write the session ID for a thread+role pair into the cache. */
+export async function setCachedSessionId(
+  threadId: ThreadId,
+  role: string,
+  sessionId: string,
+): Promise<void> {
+  const cache = await readCache();
+  cache[cacheKey(threadId, role)] = sessionId;
+  await writeCache(cache);
+}