diff --git a/packages/uwf-agent-hermes/__tests__/session-detail.test.ts b/packages/uwf-agent-hermes/__tests__/session-detail.test.ts
new file mode 100644
index 0000000..311b098
--- /dev/null
+++ b/packages/uwf-agent-hermes/__tests__/session-detail.test.ts
@@ -0,0 +1,121 @@
+import { describe, expect, test } from "bun:test";
+import { createMemoryStore, refs, validate, walk } from "@uncaged/json-cas";
+
+import {
+  computeDurationMs,
+  extractLastAssistantContent,
+  messageToTurnPayload,
+  parseSessionIdFromStdout,
+  storeHermesSessionDetail,
+} from "../src/session-detail.js";
+import type { HermesSessionJson, HermesSessionMessage } from "../src/types.js";
+
+describe("parseSessionIdFromStdout", () => {
+  test("reads session_id from the last non-empty line", () => {
+    const stdout = "Done.\n\nsession_id: 20260518_223724_45ab80\n";
+    expect(parseSessionIdFromStdout(stdout)).toBe("20260518_223724_45ab80");
+  });
+
+  test("returns null when trailing line is not session_id", () => {
+    expect(parseSessionIdFromStdout("only assistant text\n")).toBeNull();
+  });
+});
+
+describe("messageToTurnPayload", () => {
+  test("maps assistant tool_calls to toolCalls", () => {
+    const msg: HermesSessionMessage = {
+      role: "assistant",
+      content: "",
+      reasoning: null,
+      tool_calls: [{ function: { name: "read_file", arguments: '{"path":"x"}' } }],
+    };
+    const turn = messageToTurnPayload(msg, 0);
+    expect(turn).toEqual({
+      index: 0,
+      role: "assistant",
+      content: "",
+      toolCalls: [{ name: "read_file", args: '{"path":"x"}' }],
+      reasoning: null,
+    });
+  });
+
+  test("skips user messages", () => {
+    const msg: HermesSessionMessage = {
+      role: "user",
+      content: "hi",
+      reasoning: null,
+      tool_calls: null,
+    };
+    expect(messageToTurnPayload(msg, 0)).toBeNull();
+  });
+});
+
+describe("extractLastAssistantContent", () => {
+  test("returns the last non-empty assistant content", () => {
+    const messages: HermesSessionMessage[] = [
+      { role: "assistant", content: "first", reasoning: null, tool_calls: null },
+      { role: "tool", content: "tool output", reasoning: null, tool_calls: null },
+      { role: "assistant", content: "", reasoning: null, tool_calls: null },
+      { role: "assistant", content: "final answer", reasoning: null, tool_calls: null },
+    ];
+    expect(extractLastAssistantContent(messages)).toBe("final answer");
+  });
+});
+
+describe("computeDurationMs", () => {
+  test("computes elapsed time from session_start", () => {
+    const now = Date.parse("2026-05-18T13:32:59.028640Z");
+    const duration = computeDurationMs("2026-05-18T13:31:59.028640Z", now);
+    expect(duration).toBe(60_000);
+  });
+});
+
+describe("storeHermesSessionDetail", () => {
+  test("stores hermes-detail root with cas_ref turns walkable", async () => {
+    const session: HermesSessionJson = {
+      session_id: "20260518_133159_6a84e8",
+      model: "claude-opus-4.6",
+      session_start: "2026-05-18T13:31:59.028640",
+      messages: [
+        { role: "user", content: "task", reasoning: null, tool_calls: null },
+        {
+          role: "assistant",
+          content: "",
+          reasoning: "thinking",
+          tool_calls: [{ function: { name: "terminal", arguments: "{}" } }],
+        },
+        { role: "tool", content: "ok", reasoning: null, tool_calls: null },
+        { role: "assistant", content: "done", reasoning: null, tool_calls: null },
+      ],
+    };
+
+    const store = createMemoryStore();
+    const now = Date.parse("2026-05-18T13:32:59.028640");
+    const { detailHash, output } = await storeHermesSessionDetail(store, session, now);
+
+    expect(output).toBe("done");
+
+    const detailNode = store.get(detailHash);
+    expect(detailNode).not.toBeNull();
+    if (detailNode === null) {
+      return;
+    }
+    expect(validate(store, detailNode)).toBe(true);
+    expect(detailNode.payload).toMatchObject({
+      sessionId: "20260518_133159_6a84e8",
+      model: "claude-opus-4.6",
+      duration: 60_000,
+      turnCount: 3,
+    });
+
+    const turnRefs = refs(store, detailNode);
+    expect(turnRefs).toHaveLength(3);
+
+    const visited: string[] = [];
+    walk(store, detailHash, (hash) => visited.push(hash));
+    expect(visited).toContain(detailHash);
+    for (const turnHash of turnRefs) {
+      expect(visited).toContain(turnHash);
+    }
+  });
+});
diff --git a/packages/uwf-agent-hermes/src/hermes.ts b/packages/uwf-agent-hermes/src/hermes.ts
index 3aab684..aa093b6 100644
--- a/packages/uwf-agent-hermes/src/hermes.ts
+++ b/packages/uwf-agent-hermes/src/hermes.ts
@@ -1,6 +1,5 @@
 import { spawn } from "node:child_process";
 
-import { bootstrap, type JSONSchema, putSchema } from "@uncaged/json-cas";
 import {
   type AgentContext,
   type AgentRunResult,
@@ -9,19 +8,16 @@ import {
   resolveStorageRoot,
 } from "@uncaged/uwf-agent-kit";
 
+import {
+  loadHermesSession,
+  parseSessionIdFromStdout,
+  storeHermesRawOutput,
+  storeHermesSessionDetail,
+} from "./session-detail.js";
+
 const HERMES_COMMAND = "hermes";
 const HERMES_MAX_TURNS = 90;
 
-const HERMES_RAW_OUTPUT_SCHEMA: JSONSchema = {
-  title: "hermes-raw-output",
-  type: "object",
-  required: ["text"],
-  properties: {
-    text: { type: "string" },
-  },
-  additionalProperties: false,
-};
-
 function buildHistorySummary(history: AgentContext["history"]): string {
   if (history.length === 0) {
     return "";
@@ -93,18 +89,22 @@ function spawnHermesChat(prompt: string): Promise<string> {
   });
 }
 
-async function storeHermesRawOutput(rawOutput: string): Promise<string> {
-  const storageRoot = resolveStorageRoot();
-  const { store } = await createAgentStore(storageRoot);
-  await bootstrap(store);
-  const schemaHash = await putSchema(store, HERMES_RAW_OUTPUT_SCHEMA);
-  return store.put(schemaHash, { text: rawOutput });
-}
-
 async function runHermes(ctx: AgentContext): Promise<AgentRunResult> {
   const fullPrompt = buildHermesPrompt(ctx);
   const rawOutput = await spawnHermesChat(fullPrompt);
-  const detailHash = await storeHermesRawOutput(rawOutput);
+  const storageRoot = resolveStorageRoot();
+  const { store } = await createAgentStore(storageRoot);
+
+  const sessionId = parseSessionIdFromStdout(rawOutput);
+  if (sessionId !== null) {
+    const session = await loadHermesSession(sessionId);
+    if (session !== null) {
+      const { detailHash, output } = await storeHermesSessionDetail(store, session);
+      return { output, detailHash };
+    }
+  }
+
+  const detailHash = await storeHermesRawOutput(store, rawOutput);
   return { output: rawOutput, detailHash };
 }
 
diff --git a/packages/uwf-agent-hermes/src/schemas.ts b/packages/uwf-agent-hermes/src/schemas.ts
new file mode 100644
index 0000000..6d62183
--- /dev/null
+++ b/packages/uwf-agent-hermes/src/schemas.ts
@@ -0,0 +1,57 @@
+import type { JSONSchema } from "@uncaged/json-cas";
+
+const HERMES_TOOL_CALL_SCHEMA: JSONSchema = {
+  type: "object",
+  required: ["name", "args"],
+  properties: {
+    name: { type: "string" },
+    args: { type: "string" },
+  },
+  additionalProperties: false,
+};
+
+export const HERMES_TURN_SCHEMA: JSONSchema = {
+  title: "hermes-turn",
+  type: "object",
+  required: ["index", "role", "content"],
+  properties: {
+    index: { type: "integer" },
+    role: { type: "string", enum: ["assistant", "tool"] },
+    content: { type: "string" },
+    toolCalls: {
+      anyOf: [{ type: "array", items: HERMES_TOOL_CALL_SCHEMA }, { type: "null" }],
+    },
+    reasoning: {
+      anyOf: [{ type: "string" }, { type: "null" }],
+    },
+  },
+  additionalProperties: false,
+};
+
+export const HERMES_DETAIL_SCHEMA: JSONSchema = {
+  title: "hermes-detail",
+  type: "object",
+  required: ["sessionId", "model", "duration", "turnCount", "turns"],
+  properties: {
+    sessionId: { type: "string" },
+    model: { type: "string" },
+    duration: { type: "integer" },
+    turnCount: { type: "integer" },
+    turns: {
+      type: "array",
+      items: { type: "string", format: "cas_ref" },
+    },
+  },
+  additionalProperties: false,
+};
+
+/** Fallback detail when Hermes session file is unavailable. */
+export const HERMES_RAW_OUTPUT_SCHEMA: JSONSchema = {
+  title: "hermes-raw-output",
+  type: "object",
+  required: ["text"],
+  properties: {
+    text: { type: "string" },
+  },
+  additionalProperties: false,
+};
diff --git a/packages/uwf-agent-hermes/src/session-detail.ts b/packages/uwf-agent-hermes/src/session-detail.ts
new file mode 100644
index 0000000..3e29f6d
--- /dev/null
+++ b/packages/uwf-agent-hermes/src/session-detail.ts
@@ -0,0 +1,228 @@
+import { readFile } from "node:fs/promises";
+import { homedir } from "node:os";
+import { join } from "node:path";
+
+import { bootstrap, putSchema, type Store } from "@uncaged/json-cas";
+
+import { HERMES_DETAIL_SCHEMA, HERMES_RAW_OUTPUT_SCHEMA, HERMES_TURN_SCHEMA } from "./schemas.js";
+import type {
+  HermesDetailPayload,
+  HermesSessionJson,
+  HermesSessionMessage,
+  HermesToolCall,
+  HermesTurnPayload,
+  HermesTurnRole,
+} from "./types.js";
+
+const SESSION_ID_LINE = /^session_id:\s*(\S+)\s*$/i;
+
+export function getHermesSessionsDir(): string {
+  return join(homedir(), ".hermes", "sessions");
+}
+
+export function getHermesSessionPath(sessionId: string): string {
+  return join(getHermesSessionsDir(), `session_${sessionId}.json`);
+}
+
+/** Parse `session_id: …` from the last non-empty line of Hermes stdout. */
+export function parseSessionIdFromStdout(stdout: string): string | null {
+  const lines = stdout.split(/\r?\n/).map((line) => line.trim());
+  for (let i = lines.length - 1; i >= 0; i--) {
+    const line = lines[i];
+    if (line === undefined || line === "") {
+      continue;
+    }
+    const match = SESSION_ID_LINE.exec(line);
+    if (match?.[1] !== undefined) {
+      return match[1];
+    }
+    break;
+  }
+  return null;
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function parseToolCalls(raw: unknown): HermesSessionMessage["tool_calls"] {
+  if (!Array.isArray(raw) || raw.length === 0) {
+    return null;
+  }
+  const calls: NonNullable<HermesSessionMessage["tool_calls"]> = [];
+  for (const entry of raw) {
+    if (!isRecord(entry)) {
+      continue;
+    }
+    const fn = entry.function;
+    if (!isRecord(fn)) {
+      continue;
+    }
+    const name = fn.name;
+    const args = fn.arguments;
+    if (typeof name !== "string" || typeof args !== "string") {
+      continue;
+    }
+    calls.push({ function: { name, arguments: args } });
+  }
+  return calls.length > 0 ? calls : null;
+}
+
+function normalizeMessage(raw: unknown): HermesSessionMessage | null {
+  if (!isRecord(raw)) {
+    return null;
+  }
+  const role = raw.role;
+  if (role !== "assistant" && role !== "tool" && role !== "user") {
+    return null;
+  }
+  const content = typeof raw.content === "string" ? raw.content : raw.content === null ? null : "";
+  const reasoning =
+    typeof raw.reasoning === "string"
+      ? raw.reasoning
+      : raw.reasoning === null || raw.reasoning === undefined
+        ? null
+        : null;
+  const tool_calls = parseToolCalls(raw.tool_calls);
+  return { role, content, reasoning, tool_calls };
+}
+
+function parseSessionJson(raw: unknown): HermesSessionJson | null {
+  if (!isRecord(raw)) {
+    return null;
+  }
+  const session_id = raw.session_id;
+  const model = raw.model;
+  const session_start = raw.session_start;
+  const messagesRaw = raw.messages;
+  if (
+    typeof session_id !== "string" ||
+    typeof model !== "string" ||
+    typeof session_start !== "string" ||
+    !Array.isArray(messagesRaw)
+  ) {
+    return null;
+  }
+  const messages: HermesSessionMessage[] = [];
+  for (const entry of messagesRaw) {
+    const msg = normalizeMessage(entry);
+    if (msg !== null) {
+      messages.push(msg);
+    }
+  }
+  return { session_id, model, session_start, messages };
+}
+
+export async function loadHermesSession(sessionId: string): Promise<HermesSessionJson | null> {
+  const path = getHermesSessionPath(sessionId);
+  try {
+    const text = await readFile(path, "utf8");
+    const raw = JSON.parse(text) as unknown;
+    return parseSessionJson(raw);
+  } catch {
+    return null;
+  }
+}
+
+export function computeDurationMs(sessionStart: string, nowMs: number = Date.now()): number {
+  const startMs = Date.parse(sessionStart);
+  if (Number.isNaN(startMs)) {
+    return 0;
+  }
+  return Math.max(0, nowMs - startMs);
+}
+
+function mapSessionToolCalls(
+  toolCalls: HermesSessionMessage["tool_calls"],
+): HermesToolCall[] | null {
+  if (toolCalls === null || toolCalls.length === 0) {
+    return null;
+  }
+  return toolCalls.map((call) => ({
+    name: call.function.name,
+    args: call.function.arguments,
+  }));
+}
+
+export function messageToTurnPayload(
+  message: HermesSessionMessage,
+  index: number,
+): HermesTurnPayload | null {
+  if (message.role !== "assistant" && message.role !== "tool") {
+    return null;
+  }
+  const role = message.role as HermesTurnRole;
+  return {
+    index,
+    role,
+    content: message.content ?? "",
+    toolCalls: mapSessionToolCalls(message.tool_calls),
+    reasoning: message.reasoning,
+  };
+}
+
+/** Last assistant message with non-empty text content (walks backward). */
+export function extractLastAssistantContent(messages: HermesSessionMessage[]): string {
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const msg = messages[i];
+    if (msg === undefined) {
+      continue;
+    }
+    if (msg.role === "assistant" && msg.content !== null && msg.content.trim() !== "") {
+      return msg.content;
+    }
+  }
+  return "";
+}
+
+type HermesSchemaHashes = {
+  turn: string;
+  detail: string;
+  rawOutput: string;
+};
+
+async function registerHermesSchemas(store: Store): Promise<HermesSchemaHashes> {
+  await bootstrap(store);
+  const [turn, detail, rawOutput] = await Promise.all([
+    putSchema(store, HERMES_TURN_SCHEMA),
+    putSchema(store, HERMES_DETAIL_SCHEMA),
+    putSchema(store, HERMES_RAW_OUTPUT_SCHEMA),
+  ]);
+  return { turn, detail, rawOutput };
+}
+
+export async function storeHermesSessionDetail(
+  store: Store,
+  session: HermesSessionJson,
+  nowMs: number = Date.now(),
+): Promise<{ detailHash: string; output: string }> {
+  const schemas = await registerHermesSchemas(store);
+  const turnHashes: string[] = [];
+  let turnIndex = 0;
+
+  for (const message of session.messages) {
+    const turn = messageToTurnPayload(message, turnIndex);
+    if (turn === null) {
+      continue;
+    }
+    const hash = await store.put(schemas.turn, turn);
+    turnHashes.push(hash);
+    turnIndex += 1;
+  }
+
+  const detail: HermesDetailPayload = {
+    sessionId: session.session_id,
+    model: session.model,
+    duration: computeDurationMs(session.session_start, nowMs),
+    turnCount: turnHashes.length,
+    turns: turnHashes,
+  };
+  const detailHash = await store.put(schemas.detail, detail);
+  const output = extractLastAssistantContent(session.messages);
+  return { detailHash, output };
+}
+
+export async function storeHermesRawOutput(store: Store, rawOutput: string): Promise<string> {
+  const schemas = await registerHermesSchemas(store);
+  return store.put(schemas.rawOutput, { text: rawOutput });
+}
diff --git a/packages/uwf-agent-hermes/src/types.ts b/packages/uwf-agent-hermes/src/types.ts
new file mode 100644
index 0000000..4aa32cf
--- /dev/null
+++ b/packages/uwf-agent-hermes/src/types.ts
@@ -0,0 +1,43 @@
+export type HermesTurnRole = "assistant" | "tool";
+
+export type HermesToolCall = {
+  name: string;
+  args: string;
+};
+
+export type HermesTurnPayload = {
+  index: number;
+  role: HermesTurnRole;
+  content: string;
+  toolCalls: HermesToolCall[] | null;
+  reasoning: string | null;
+};
+
+export type HermesDetailPayload = {
+  sessionId: string;
+  model: string;
+  duration: number;
+  turnCount: number;
+  turns: string[];
+};
+
+export type HermesSessionToolCall = {
+  function: {
+    name: string;
+    arguments: string;
+  };
+};
+
+export type HermesSessionMessage = {
+  role: string;
+  content: string | null;
+  tool_calls: HermesSessionToolCall[] | null;
+  reasoning: string | null;
+};
+
+export type HermesSessionJson = {
+  session_id: string;
+  model: string;
+  session_start: string;
+  messages: HermesSessionMessage[];
+};