story-kit: merge 271_story_show_assigned_agent_in_expanded_work_item_view

Adds assigned agent display to the expanded work item detail panel.
Resolved conflicts by keeping master versions of bot.rs (permission
handling), ChatInput.tsx, and fs.rs. Removed duplicate list_project_files
endpoint and tests from io.rs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.story_kit/work/1_upcoming/266_story_matrix_bot_structured_conversation_history.md

@@ -1,60 +0,0 @@
----
-name: "Matrix bot structured conversation history"
-agent: coder-opus
----
-
-# Story 266: Matrix bot structured conversation history
-
-## User Story
-
-As a user chatting with the Matrix bot, I want it to remember and own its prior responses naturally, so that conversations feel like talking to one continuous entity rather than a new instance each message.
-
-## Acceptance Criteria
-
-- [ ] Conversation history is passed as structured API messages (user/assistant turns) rather than a flattened text prefix
-- [ ] Claude recognises its prior responses as its own, maintaining consistent personality across a conversation
-- [ ] Per-room history survives server restarts (persisted to disk or database)
-- [ ] Rolling window trimming still applies to keep context bounded
-- [ ] Multi-user rooms still attribute messages to the correct sender
-
-## Investigation Notes (2026-03-18)
-
-The current implementation attempts session resumption via `--resume <session_id>` but it's not working:
-
-### Code path: how session resumption is supposed to work
-
-1. `server/src/matrix/bot.rs:671-676` — `handle_message()` reads `conv.session_id` from the per-room `RoomConversation` to get the resume ID.
-2. `server/src/matrix/bot.rs:717` — passes `resume_session_id` to `provider.chat_stream()`.
-3. `server/src/llm/providers/claude_code.rs:57` — `chat_stream()` stores it as `resume_id`.
-4. `server/src/llm/providers/claude_code.rs:170-173` — if `resume_session_id` is `Some`, appends `--resume <id>` to the `claude -p` command.
-5. `server/src/llm/providers/claude_code.rs:348` — `process_json_event()` looks for `json["session_id"]` in each streamed NDJSON event and sends it via a oneshot channel (`sid_tx`).
-6. `server/src/llm/providers/claude_code.rs:122` — after the PTY exits, `sid_rx.await.ok()` captures the session ID (or `None` if never sent).
-7. `server/src/matrix/bot.rs:785-787` — stores `new_session_id` back into `conv.session_id` and persists via `save_history()`.
-
-### What's broken
-
-- **No session_id captured:** `.story_kit/matrix_history.json` contains conversation entries but no `session_id`. `RoomConversation.session_id` is always `None`.
-- **Root cause:** `claude -p --output-format stream-json` may not emit a `session_id` in its NDJSON events, or the parser at step 5 isn't matching the actual event shape. The oneshot channel never fires.
-- **Effect:** Every message spawns a fresh Claude Code process with no `--resume` flag. Each turn is a blank slate.
-- **History persistence works fine** — serialization round-trips correctly (test at `bot.rs:1335-1339`). The problem is purely that `--resume` is never invoked.
-
-### Debugging steps
-
-1. Run `claude -p "hello" --output-format stream-json --verbose 2>/dev/null` manually and inspect the NDJSON for a `session_id` field. Check what event type carries it and whether the key name matches what `process_json_event()` expects.
-2. If `session_id` is present but nested differently (e.g. inside an `event` wrapper), fix the JSON path at `claude_code.rs:348`.
-3. If `-p` mode doesn't emit `session_id` at all, consider an alternative: pass conversation history as a structured prompt prefix, or switch to the Claude API directly.
-
-### Previous attempt failed (2026-03-18)
-
-A sonnet coder attempted this story but did NOT fix the root cause. It rewrote the `chat_stream()` call in `bot.rs` to look identical to what was already there — it never investigated why `session_id` isn't being captured. The merge auto-resolver then jammed the duplicate call inside the `tokio::select!` permission loop, producing mismatched braces. The broken merge was reverted.
-
-**What the coder must actually do:**
-
-1. **Do NOT rewrite the `chat_stream()` call or the `tokio::select!` loop in `bot.rs`.** That code is correct and handles permission forwarding (story 275). Do not touch it.
-2. **The bug is in `claude_code.rs`, not `bot.rs`.** The `process_json_event()` function at line ~348 looks for `json["session_id"]` but it's likely never finding it. Start by running step 1 above to see what the actual NDJSON output looks like.
-3. **If `claude -p` doesn't emit `session_id` at all**, the `--resume` approach won't work. In that case, the fix is to pass conversation history as a prompt prefix (prepend prior turns to the user message) or use `--continue` instead of `--resume`, or call the Claude API directly instead of shelling out to the CLI.
-4. **Rebase onto current master before starting.** Master has changed significantly (spike 92, story 275 permission handling, gitignore changes).
-
-## Out of Scope
-
-- TBD

.story_kit/work/1_upcoming/276_story_detect_and_log_when_root_mcp_json_port_is_modified.md

@@ -1,17 +0,0 @@
----
-name: "Detect and log when root .mcp.json port is modified"
----
-
-# Story 276: Detect and log when root .mcp.json port is modified
-
-## User Story
-
-As a ..., I want ..., so that ...
-
-## Acceptance Criteria
-
-- [ ] TODO
-
-## Out of Scope
-
-- TBD

.story_kit/work/6_archived/266_story_matrix_bot_structured_conversation_history.md

@@ -0,0 +1,21 @@
+---
+name: "Matrix bot structured conversation history"
+---
+
+# Story 266: Matrix bot structured conversation history
+
+## User Story
+
+As a user chatting with the Matrix bot, I want it to remember and own its prior responses naturally, so that conversations feel like talking to one continuous entity rather than a new instance each message.
+
+## Acceptance Criteria
+
+- [ ] Conversation history is passed as structured API messages (user/assistant turns) rather than a flattened text prefix
+- [ ] Claude recognises its prior responses as its own, maintaining consistent personality across a conversation
+- [ ] Per-room history survives server restarts (persisted to disk or database)
+- [ ] Rolling window trimming still applies to keep context bounded
+- [ ] Multi-user rooms still attribute messages to the correct sender
+
+## Out of Scope
+
+- TBD

frontend/src/api/client.ts

@@ -115,6 +115,7 @@ export interface WorkItemContent {
 	content: string;
 	stage: string;
 	name: string | null;
+	agent: string | null;
 }
 
 export interface TestCaseResult {

frontend/src/components/Chat.test.tsx

@@ -38,6 +38,8 @@ vi.mock("../api/client", () => {
 		setModelPreference: vi.fn(),
 		cancelChat: vi.fn(),
 		setAnthropicApiKey: vi.fn(),
+		readFile: vi.fn(),
+		listProjectFiles: vi.fn(),
 	};
 	class ChatWebSocket {
 		connect(handlers: WsHandlers) {
@@ -60,6 +62,8 @@ const mockedApi = {
 	setModelPreference: vi.mocked(api.setModelPreference),
 	cancelChat: vi.mocked(api.cancelChat),
 	setAnthropicApiKey: vi.mocked(api.setAnthropicApiKey),
+	readFile: vi.mocked(api.readFile),
+	listProjectFiles: vi.mocked(api.listProjectFiles),
 };
 
 function setupMocks() {
@@ -68,6 +72,8 @@ function setupMocks() {
 	mockedApi.getAnthropicModels.mockResolvedValue([]);
 	mockedApi.getModelPreference.mockResolvedValue(null);
 	mockedApi.setModelPreference.mockResolvedValue(true);
+	mockedApi.readFile.mockResolvedValue("");
+	mockedApi.listProjectFiles.mockResolvedValue([]);
 	mockedApi.cancelChat.mockResolvedValue(true);
 	mockedApi.setAnthropicApiKey.mockResolvedValue(true);
 }
@@ -625,7 +631,7 @@ describe("Chat localStorage persistence (Story 145)", () => {
 
 		// Verify sendChat was called with ALL prior messages + the new one
 		expect(lastSendChatArgs).not.toBeNull();
-		const args = lastSendChatArgs!;
+		const args = lastSendChatArgs as NonNullable<typeof lastSendChatArgs>;
 		expect(args.messages).toHaveLength(3);
 		expect(args.messages[0]).toEqual({
 			role: "user",
@@ -1344,7 +1350,7 @@ describe("Bug 264: Claude Code session ID persisted across browser refresh", ()
 
 		expect(lastSendChatArgs).not.toBeNull();
 		expect(
-			(lastSendChatArgs!.config as Record<string, unknown>).session_id,
+			(lastSendChatArgs?.config as Record<string, unknown>).session_id,
 		).toBe("persisted-session-xyz");
 	});
 
@@ -1387,3 +1393,57 @@ describe("Bug 264: Claude Code session ID persisted across browser refresh", ()
 		expect(localStorage.getItem(otherKey)).toBe("other-session");
 	});
 });
+
+describe("File reference expansion (Story 269 AC4)", () => {
+	beforeEach(() => {
+		vi.clearAllMocks();
+		capturedWsHandlers = null;
+		lastSendChatArgs = null;
+		setupMocks();
+	});
+
+	it("includes file contents as context when message contains @file reference", async () => {
+		mockedApi.readFile.mockResolvedValue('fn main() { println!("hello"); }');
+
+		render(<Chat projectPath="/tmp/project" onCloseProject={vi.fn()} />);
+		await waitFor(() => expect(capturedWsHandlers).not.toBeNull());
+
+		const input = screen.getByPlaceholderText("Send a message...");
+		await act(async () => {
+			fireEvent.change(input, { target: { value: "explain @src/main.rs" } });
+		});
+		await act(async () => {
+			fireEvent.keyDown(input, { key: "Enter", shiftKey: false });
+		});
+
+		await waitFor(() => expect(lastSendChatArgs).not.toBeNull());
+		const sentMessages = (
+			lastSendChatArgs as NonNullable<typeof lastSendChatArgs>
+		).messages;
+		const userMsg = sentMessages[sentMessages.length - 1];
+		expect(userMsg.content).toContain("explain @src/main.rs");
+		expect(userMsg.content).toContain("[File: src/main.rs]");
+		expect(userMsg.content).toContain("fn main()");
+	});
+
+	it("sends message without modification when no @file references are present", async () => {
+		render(<Chat projectPath="/tmp/project" onCloseProject={vi.fn()} />);
+		await waitFor(() => expect(capturedWsHandlers).not.toBeNull());
+
+		const input = screen.getByPlaceholderText("Send a message...");
+		await act(async () => {
+			fireEvent.change(input, { target: { value: "hello world" } });
+		});
+		await act(async () => {
+			fireEvent.keyDown(input, { key: "Enter", shiftKey: false });
+		});
+
+		await waitFor(() => expect(lastSendChatArgs).not.toBeNull());
+		const sentMessages = (
+			lastSendChatArgs as NonNullable<typeof lastSendChatArgs>
+		).messages;
+		const userMsg = sentMessages[sentMessages.length - 1];
+		expect(userMsg.content).toBe("hello world");
+		expect(mockedApi.readFile).not.toHaveBeenCalled();
+	});
+});

frontend/src/components/Chat.tsx

@@ -554,7 +554,26 @@ export function Chat({ projectPath, onCloseProject }: ChatProps) {
 			}
 		}
 
-		const userMsg: Message = { role: "user", content: messageText };
+		// Expand @file references: append file contents as context
+		const fileRefs = [...messageText.matchAll(/(^|[\s\n])@([^\s@]+)/g)].map(
+			(m) => m[2],
+		);
+		let expandedText = messageText;
+		if (fileRefs.length > 0) {
+			const expansions = await Promise.allSettled(
+				fileRefs.map(async (ref) => {
+					const contents = await api.readFile(ref);
+					return { ref, contents };
+				}),
+			);
+			for (const result of expansions) {
+				if (result.status === "fulfilled") {
+					expandedText += `\n\n[File: ${result.value.ref}]\n\`\`\`\n${result.value.contents}\n\`\`\``;
+				}
+			}
+		}
+
+		const userMsg: Message = { role: "user", content: expandedText };
 		const newHistory = [...messages, userMsg];
 
 		setMessages(newHistory);

frontend/src/components/ChatInputFilePicker.test.tsx

@@ -0,0 +1,194 @@
+import {
+	act,
+	fireEvent,
+	render,
+	screen,
+	waitFor,
+} from "@testing-library/react";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { api } from "../api/client";
+import { ChatInput } from "./ChatInput";
+
+vi.mock("../api/client", () => ({
+	api: {
+		listProjectFiles: vi.fn(),
+	},
+}));
+
+const mockedListProjectFiles = vi.mocked(api.listProjectFiles);
+
+const defaultProps = {
+	loading: false,
+	queuedMessages: [],
+	onSubmit: vi.fn(),
+	onCancel: vi.fn(),
+	onRemoveQueuedMessage: vi.fn(),
+};
+
+beforeEach(() => {
+	vi.clearAllMocks();
+	mockedListProjectFiles.mockResolvedValue([
+		"src/main.rs",
+		"src/lib.rs",
+		"frontend/index.html",
+		"README.md",
+	]);
+});
+
+describe("File picker overlay (Story 269 AC1)", () => {
+	it("shows file picker overlay when @ is typed", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+	});
+
+	it("does not show file picker overlay for text without @", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "hello world" } });
+		});
+
+		expect(screen.queryByTestId("file-picker-overlay")).not.toBeInTheDocument();
+	});
+});
+
+describe("File picker fuzzy matching (Story 269 AC2)", () => {
+	it("filters files by query typed after @", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@main" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+
+		// main.rs should be visible, README.md should not
+		expect(screen.getByText("src/main.rs")).toBeInTheDocument();
+		expect(screen.queryByText("README.md")).not.toBeInTheDocument();
+	});
+
+	it("shows all files when @ is typed with no query", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+
+		// All 4 files should be visible
+		expect(screen.getByText("src/main.rs")).toBeInTheDocument();
+		expect(screen.getByText("src/lib.rs")).toBeInTheDocument();
+		expect(screen.getByText("README.md")).toBeInTheDocument();
+	});
+});
+
+describe("File picker selection (Story 269 AC3)", () => {
+	it("clicking a file inserts @path into the message", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-item-0")).toBeInTheDocument();
+		});
+
+		await act(async () => {
+			fireEvent.click(screen.getByTestId("file-picker-item-0"));
+		});
+
+		// Picker should be dismissed and the file reference inserted
+		expect(screen.queryByTestId("file-picker-overlay")).not.toBeInTheDocument();
+		expect((textarea as HTMLTextAreaElement).value).toMatch(/^@\S+/);
+	});
+
+	it("Enter key selects highlighted file and inserts it into message", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@main" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+
+		await act(async () => {
+			fireEvent.keyDown(textarea, { key: "Enter" });
+		});
+
+		expect(screen.queryByTestId("file-picker-overlay")).not.toBeInTheDocument();
+		expect((textarea as HTMLTextAreaElement).value).toContain("@src/main.rs");
+	});
+});
+
+describe("File picker dismiss (Story 269 AC5)", () => {
+	it("Escape key dismisses the file picker", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+
+		await act(async () => {
+			fireEvent.keyDown(textarea, { key: "Escape" });
+		});
+
+		expect(screen.queryByTestId("file-picker-overlay")).not.toBeInTheDocument();
+	});
+});
+
+describe("Multiple @ references (Story 269 AC6)", () => {
+	it("typing @ after a completed reference triggers picker again", async () => {
+		render(<ChatInput {...defaultProps} />);
+		const textarea = screen.getByPlaceholderText("Send a message...");
+
+		// First reference
+		await act(async () => {
+			fireEvent.change(textarea, { target: { value: "@main" } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+
+		// Select file
+		await act(async () => {
+			fireEvent.keyDown(textarea, { key: "Enter" });
+		});
+
+		// Type a second @
+		await act(async () => {
+			const current = (textarea as HTMLTextAreaElement).value;
+			fireEvent.change(textarea, { target: { value: `${current} @` } });
+		});
+
+		await waitFor(() => {
+			expect(screen.getByTestId("file-picker-overlay")).toBeInTheDocument();
+		});
+	});
+});

frontend/src/components/WorkItemDetailPanel.test.tsx

@@ -37,6 +37,7 @@ const DEFAULT_CONTENT = {
 	content: "# Big Title\n\nSome content here.",
 	stage: "current",
 	name: "Big Title Story",
+	agent: null,
 };
 
 const sampleTestResults: TestResultsResponse = {
@@ -436,6 +437,60 @@ describe("WorkItemDetailPanel - Agent Logs", () => {
 	});
 });
 
+describe("WorkItemDetailPanel - Assigned Agent", () => {
+	it("shows assigned agent name when agent front matter field is set", async () => {
+		mockedGetWorkItemContent.mockResolvedValue({
+			...DEFAULT_CONTENT,
+			agent: "coder-opus",
+		});
+
+		render(
+			<WorkItemDetailPanel
+				storyId="271_story_test"
+				pipelineVersion={0}
+				onClose={() => {}}
+			/>,
+		);
+
+		const agentEl = await screen.findByTestId("detail-panel-assigned-agent");
+		expect(agentEl).toHaveTextContent("coder-opus");
+	});
+
+	it("omits assigned agent field when no agent is set in front matter", async () => {
+		render(
+			<WorkItemDetailPanel
+				storyId="271_story_test"
+				pipelineVersion={0}
+				onClose={() => {}}
+			/>,
+		);
+
+		await screen.findByTestId("detail-panel-content");
+		expect(
+			screen.queryByTestId("detail-panel-assigned-agent"),
+		).not.toBeInTheDocument();
+	});
+
+	it("shows the specific agent name not just 'assigned'", async () => {
+		mockedGetWorkItemContent.mockResolvedValue({
+			...DEFAULT_CONTENT,
+			agent: "coder-haiku",
+		});
+
+		render(
+			<WorkItemDetailPanel
+				storyId="271_story_test"
+				pipelineVersion={0}
+				onClose={() => {}}
+			/>,
+		);
+
+		const agentEl = await screen.findByTestId("detail-panel-assigned-agent");
+		expect(agentEl).toHaveTextContent("coder-haiku");
+		expect(agentEl).not.toHaveTextContent("assigned");
+	});
+});
+
 describe("WorkItemDetailPanel - Test Results", () => {
 	it("shows empty test results message when no results exist", async () => {
 		mockedGetTestResults.mockResolvedValue(null);

frontend/src/components/WorkItemDetailPanel.tsx

@@ -113,6 +113,7 @@ export function WorkItemDetailPanel({
 	const [content, setContent] = useState<string | null>(null);
 	const [stage, setStage] = useState<string>("");
 	const [name, setName] = useState<string | null>(null);
+	const [assignedAgent, setAssignedAgent] = useState<string | null>(null);
 	const [loading, setLoading] = useState(true);
 	const [error, setError] = useState<string | null>(null);
 	const [agentInfo, setAgentInfo] = useState<AgentInfo | null>(null);
@@ -133,6 +134,7 @@ export function WorkItemDetailPanel({
 				setContent(data.content);
 				setStage(data.stage);
 				setName(data.name);
+				setAssignedAgent(data.agent);
 			})
 			.catch((err: unknown) => {
 				setError(err instanceof Error ? err.message : "Failed to load content");
@@ -278,6 +280,14 @@ export function WorkItemDetailPanel({
 							{stageLabel}
 						</div>
 					)}
+					{assignedAgent ? (
+						<div
+							data-testid="detail-panel-assigned-agent"
+							style={{ fontSize: "0.75em", color: "#888" }}
+						>
+							Agent: {assignedAgent}
+						</div>
+					) : null}
 				</div>
 				<button
 					type="button"

server/src/http/agents.rs

@@ -68,6 +68,7 @@ struct WorkItemContentResponse {
     content: String,
     stage: String,
     name: Option<String>,
+    agent: Option<String>,
 }
 
 /// A single test case result for the OpenAPI response.
@@ -354,13 +355,14 @@ impl AgentsApi {
             if file_path.exists() {
                 let content = std::fs::read_to_string(&file_path)
                     .map_err(|e| bad_request(format!("Failed to read work item: {e}")))?;
-                let name = crate::io::story_metadata::parse_front_matter(&content)
+                let metadata = crate::io::story_metadata::parse_front_matter(&content).ok();
-                    .ok()
+                let name = metadata.as_ref().and_then(|m| m.name.clone());
-                    .and_then(|m| m.name);
+                let agent = metadata.and_then(|m| m.agent);
                 return Ok(Json(WorkItemContentResponse {
                     content,
                     stage: stage_name.to_string(),
                     name,
+                    agent,
                 }));
             }
         }

server/src/http/io.rs

@@ -401,4 +401,5 @@ mod tests {
         let result = api.list_directory(payload).await;
         assert!(result.is_err());
     }
+
 }