Merge story-29: Backfill tests for maximum coverage

Adds 57 Rust tests and 60 frontend tests across 4 batches:
- Batch 1: store, search, workflow
- Batch 2: fs, shell, http/workflow
- Batch 3: usePathCompletion, api/client, api/workflow
- Batch 4: App, GatePanel, ReviewPanel

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/App.test.tsx

@@ -0,0 +1,158 @@
+import { render, screen, waitFor } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { api } from "./api/client";
+
+vi.mock("./api/client", () => {
+	const api = {
+		getCurrentProject: vi.fn(),
+		getKnownProjects: vi.fn(),
+		getHomeDirectory: vi.fn(),
+		openProject: vi.fn(),
+		closeProject: vi.fn(),
+		forgetKnownProject: vi.fn(),
+		listDirectoryAbsolute: vi.fn(),
+		getOllamaModels: vi.fn(),
+		getAnthropicApiKeyExists: vi.fn(),
+		getAnthropicModels: vi.fn(),
+		getModelPreference: vi.fn(),
+		setModelPreference: vi.fn(),
+		cancelChat: vi.fn(),
+		setAnthropicApiKey: vi.fn(),
+	};
+	class ChatWebSocket {
+		connect() {}
+		close() {}
+		sendChat() {}
+		cancel() {}
+	}
+	return { api, ChatWebSocket };
+});
+
+vi.mock("./api/workflow", () => {
+	return {
+		workflowApi: {
+			getAcceptance: vi.fn().mockResolvedValue({
+				can_accept: false,
+				reasons: [],
+				warning: null,
+				summary: { total: 0, passed: 0, failed: 0 },
+				missing_categories: [],
+			}),
+			getReviewQueueAll: vi.fn().mockResolvedValue({ stories: [] }),
+			recordTests: vi.fn(),
+			ensureAcceptance: vi.fn(),
+			getReviewQueue: vi.fn(),
+		},
+	};
+});
+
+const mockedApi = vi.mocked(api);
+
+describe("App", () => {
+	beforeEach(() => {
+		vi.resetModules();
+		vi.clearAllMocks();
+		mockedApi.getKnownProjects.mockResolvedValue([]);
+		mockedApi.getHomeDirectory.mockResolvedValue("/home/user");
+		mockedApi.listDirectoryAbsolute.mockResolvedValue([]);
+		mockedApi.getOllamaModels.mockResolvedValue([]);
+		mockedApi.getAnthropicApiKeyExists.mockResolvedValue(false);
+		mockedApi.getAnthropicModels.mockResolvedValue([]);
+		mockedApi.getModelPreference.mockResolvedValue(null);
+	});
+
+	async function renderApp() {
+		const { default: App } = await import("./App");
+		return render(<App />);
+	}
+
+	it("renders the selection screen when no project is open", async () => {
+		await renderApp();
+
+		await waitFor(() => {
+			expect(
+				screen.getByPlaceholderText(/\/path\/to\/project/i),
+			).toBeInTheDocument();
+		});
+	});
+
+	it("populates path input with home directory", async () => {
+		mockedApi.getHomeDirectory.mockResolvedValue("/Users/dave");
+
+		await renderApp();
+
+		await waitFor(() => {
+			const input = screen.getByPlaceholderText(
+				/\/path\/to\/project/i,
+			) as HTMLInputElement;
+			expect(input.value).toBe("/Users/dave/");
+		});
+	});
+
+	it("opens project and shows chat view", async () => {
+		mockedApi.openProject.mockResolvedValue("/home/user/myproject");
+
+		await renderApp();
+
+		await waitFor(() => {
+			expect(
+				screen.getByPlaceholderText(/\/path\/to\/project/i),
+			).toBeInTheDocument();
+		});
+
+		const input = screen.getByPlaceholderText(
+			/\/path\/to\/project/i,
+		) as HTMLInputElement;
+		await userEvent.clear(input);
+		await userEvent.type(input, "/home/user/myproject");
+
+		const openButton = screen.getByRole("button", { name: /open project/i });
+		await userEvent.click(openButton);
+
+		await waitFor(() => {
+			expect(mockedApi.openProject).toHaveBeenCalledWith(
+				"/home/user/myproject",
+			);
+		});
+	});
+
+	it("shows error when openProject fails", async () => {
+		mockedApi.openProject.mockRejectedValue(new Error("Path does not exist"));
+
+		await renderApp();
+
+		await waitFor(() => {
+			expect(
+				screen.getByPlaceholderText(/\/path\/to\/project/i),
+			).toBeInTheDocument();
+		});
+
+		const input = screen.getByPlaceholderText(
+			/\/path\/to\/project/i,
+		) as HTMLInputElement;
+		await userEvent.clear(input);
+		await userEvent.type(input, "/bad/path");
+
+		const openButton = screen.getByRole("button", { name: /open project/i });
+		await userEvent.click(openButton);
+
+		await waitFor(() => {
+			expect(screen.getByText(/Path does not exist/)).toBeInTheDocument();
+		});
+	});
+
+	it("shows known projects list", async () => {
+		mockedApi.getKnownProjects.mockResolvedValue([
+			"/home/user/project1",
+			"/home/user/project2",
+		]);
+
+		await renderApp();
+
+		await waitFor(() => {
+			expect(screen.getByTitle("/home/user/project1")).toBeInTheDocument();
+			expect(screen.getByTitle("/home/user/project2")).toBeInTheDocument();
+		});
+	});
+});

frontend/src/api/client.test.ts

@@ -0,0 +1,138 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { api } from "./client";
+
+const mockFetch = vi.fn();
+
+beforeEach(() => {
+	vi.stubGlobal("fetch", mockFetch);
+});
+
+afterEach(() => {
+	vi.restoreAllMocks();
+});
+
+function okResponse(body: unknown) {
+	return new Response(JSON.stringify(body), {
+		status: 200,
+		headers: { "Content-Type": "application/json" },
+	});
+}
+
+function errorResponse(status: number, text: string) {
+	return new Response(text, { status });
+}
+
+describe("api client", () => {
+	describe("getCurrentProject", () => {
+		it("sends GET to /project", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse("/home/user/project"));
+
+			const result = await api.getCurrentProject();
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/project",
+				expect.objectContaining({}),
+			);
+			expect(result).toBe("/home/user/project");
+		});
+
+		it("returns null when no project open", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse(null));
+
+			const result = await api.getCurrentProject();
+			expect(result).toBeNull();
+		});
+	});
+
+	describe("openProject", () => {
+		it("sends POST with path", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse("/home/user/project"));
+
+			await api.openProject("/home/user/project");
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/project",
+				expect.objectContaining({
+					method: "POST",
+					body: JSON.stringify({ path: "/home/user/project" }),
+				}),
+			);
+		});
+	});
+
+	describe("closeProject", () => {
+		it("sends DELETE to /project", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse(true));
+
+			await api.closeProject();
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/project",
+				expect.objectContaining({ method: "DELETE" }),
+			);
+		});
+	});
+
+	describe("getKnownProjects", () => {
+		it("returns array of project paths", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse(["/a", "/b"]));
+
+			const result = await api.getKnownProjects();
+			expect(result).toEqual(["/a", "/b"]);
+		});
+	});
+
+	describe("error handling", () => {
+		it("throws on non-ok response with body text", async () => {
+			mockFetch.mockResolvedValueOnce(errorResponse(404, "Not found"));
+
+			await expect(api.getCurrentProject()).rejects.toThrow("Not found");
+		});
+
+		it("throws with status code when no body", async () => {
+			mockFetch.mockResolvedValueOnce(errorResponse(500, ""));
+
+			await expect(api.getCurrentProject()).rejects.toThrow(
+				"Request failed (500)",
+			);
+		});
+	});
+
+	describe("searchFiles", () => {
+		it("sends POST with query", async () => {
+			mockFetch.mockResolvedValueOnce(
+				okResponse([{ path: "src/main.rs", matches: 1 }]),
+			);
+
+			const result = await api.searchFiles("hello");
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/fs/search",
+				expect.objectContaining({
+					method: "POST",
+					body: JSON.stringify({ query: "hello" }),
+				}),
+			);
+			expect(result).toHaveLength(1);
+		});
+	});
+
+	describe("execShell", () => {
+		it("sends POST with command and args", async () => {
+			mockFetch.mockResolvedValueOnce(
+				okResponse({ stdout: "output", stderr: "", exit_code: 0 }),
+			);
+
+			const result = await api.execShell("ls", ["-la"]);
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/shell/exec",
+				expect.objectContaining({
+					method: "POST",
+					body: JSON.stringify({ command: "ls", args: ["-la"] }),
+				}),
+			);
+			expect(result.exit_code).toBe(0);
+		});
+	});
+});

frontend/src/api/workflow.test.ts

@@ -0,0 +1,113 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { workflowApi } from "./workflow";
+
+const mockFetch = vi.fn();
+
+beforeEach(() => {
+	vi.stubGlobal("fetch", mockFetch);
+});
+
+afterEach(() => {
+	vi.restoreAllMocks();
+});
+
+function okResponse(body: unknown) {
+	return new Response(JSON.stringify(body), {
+		status: 200,
+		headers: { "Content-Type": "application/json" },
+	});
+}
+
+function errorResponse(status: number, text: string) {
+	return new Response(text, { status });
+}
+
+describe("workflowApi", () => {
+	describe("recordTests", () => {
+		it("sends POST to /workflow/tests/record", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse(true));
+
+			const payload = {
+				story_id: "story-29",
+				unit: [{ name: "t1", status: "pass" as const }],
+				integration: [],
+			};
+
+			await workflowApi.recordTests(payload);
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/workflow/tests/record",
+				expect.objectContaining({ method: "POST" }),
+			);
+		});
+	});
+
+	describe("getAcceptance", () => {
+		it("sends POST and returns acceptance response", async () => {
+			const response = {
+				can_accept: true,
+				reasons: [],
+				warning: null,
+				summary: { total: 2, passed: 2, failed: 0 },
+				missing_categories: [],
+			};
+			mockFetch.mockResolvedValueOnce(okResponse(response));
+
+			const result = await workflowApi.getAcceptance({
+				story_id: "story-29",
+			});
+
+			expect(result.can_accept).toBe(true);
+			expect(result.summary.total).toBe(2);
+		});
+	});
+
+	describe("getReviewQueueAll", () => {
+		it("sends GET to /workflow/review/all", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse({ stories: [] }));
+
+			const result = await workflowApi.getReviewQueueAll();
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"/api/workflow/review/all",
+				expect.objectContaining({}),
+			);
+			expect(result.stories).toEqual([]);
+		});
+	});
+
+	describe("ensureAcceptance", () => {
+		it("returns true when acceptance passes", async () => {
+			mockFetch.mockResolvedValueOnce(okResponse(true));
+
+			const result = await workflowApi.ensureAcceptance({
+				story_id: "story-29",
+			});
+
+			expect(result).toBe(true);
+		});
+
+		it("throws on error response", async () => {
+			mockFetch.mockResolvedValueOnce(
+				errorResponse(400, "Acceptance is blocked"),
+			);
+
+			await expect(
+				workflowApi.ensureAcceptance({ story_id: "story-29" }),
+			).rejects.toThrow("Acceptance is blocked");
+		});
+	});
+
+	describe("getReviewQueue", () => {
+		it("sends GET to /workflow/review", async () => {
+			mockFetch.mockResolvedValueOnce(
+				okResponse({ stories: [{ story_id: "s1", can_accept: true }] }),
+			);
+
+			const result = await workflowApi.getReviewQueue();
+
+			expect(result.stories).toHaveLength(1);
+			expect(result.stories[0].story_id).toBe("s1");
+		});
+	});
+});

frontend/src/components/GatePanel.test.tsx

@@ -0,0 +1,145 @@
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, expect, it, vi } from "vitest";
+import { GatePanel } from "./GatePanel";
+
+const baseProps = {
+	gateState: null,
+	gateStatusLabel: "Unknown",
+	gateStatusColor: "#aaa",
+	isGateLoading: false,
+	gateError: null,
+	lastGateRefresh: null,
+	onRefresh: vi.fn(),
+};
+
+describe("GatePanel", () => {
+	it("shows 'no workflow data' when gateState is null", () => {
+		render(<GatePanel {...baseProps} />);
+		expect(screen.getByText("No workflow data yet.")).toBeInTheDocument();
+	});
+
+	it("shows loading message when isGateLoading is true", () => {
+		render(<GatePanel {...baseProps} isGateLoading={true} />);
+		expect(
+			screen.getByText("Loading workflow gates..."),
+		).toBeInTheDocument();
+	});
+
+	it("shows error with retry button", async () => {
+		const onRefresh = vi.fn();
+		render(
+			<GatePanel
+				{...baseProps}
+				gateError="Connection failed"
+				onRefresh={onRefresh}
+			/>,
+		);
+
+		expect(screen.getByText("Connection failed")).toBeInTheDocument();
+
+		const retryButton = screen.getByRole("button", { name: "Retry" });
+		await userEvent.click(retryButton);
+		expect(onRefresh).toHaveBeenCalledOnce();
+	});
+
+	it("shows gate status label and color", () => {
+		render(
+			<GatePanel
+				{...baseProps}
+				gateStatusLabel="Blocked"
+				gateStatusColor="#ff7b72"
+			/>,
+		);
+		expect(screen.getByText("Blocked")).toBeInTheDocument();
+	});
+
+	it("shows test summary when gateState is provided", () => {
+		render(
+			<GatePanel
+				{...baseProps}
+				gateState={{
+					canAccept: true,
+					reasons: [],
+					warning: null,
+					summary: { total: 5, passed: 5, failed: 0 },
+					missingCategories: [],
+				}}
+				gateStatusLabel="Ready to accept"
+			/>,
+		);
+		expect(
+			screen.getByText(/5\/5 passing, 0 failing/),
+		).toBeInTheDocument();
+	});
+
+	it("shows missing categories", () => {
+		render(
+			<GatePanel
+				{...baseProps}
+				gateState={{
+					canAccept: false,
+					reasons: [],
+					warning: null,
+					summary: { total: 0, passed: 0, failed: 0 },
+					missingCategories: ["unit", "integration"],
+				}}
+			/>,
+		);
+		expect(
+			screen.getByText("Missing: unit, integration"),
+		).toBeInTheDocument();
+	});
+
+	it("shows warning text", () => {
+		render(
+			<GatePanel
+				{...baseProps}
+				gateState={{
+					canAccept: false,
+					reasons: [],
+					warning: "Multiple tests failing — fix one at a time.",
+					summary: { total: 4, passed: 2, failed: 2 },
+					missingCategories: [],
+				}}
+			/>,
+		);
+		expect(
+			screen.getByText("Multiple tests failing — fix one at a time."),
+		).toBeInTheDocument();
+	});
+
+	it("shows reasons as list items", () => {
+		render(
+			<GatePanel
+				{...baseProps}
+				gateState={{
+					canAccept: false,
+					reasons: ["No approved test plan.", "Tests are failing."],
+					warning: null,
+					summary: { total: 2, passed: 1, failed: 1 },
+					missingCategories: [],
+				}}
+			/>,
+		);
+		expect(
+			screen.getByText("No approved test plan."),
+		).toBeInTheDocument();
+		expect(screen.getByText("Tests are failing.")).toBeInTheDocument();
+	});
+
+	it("calls onRefresh when Refresh button is clicked", async () => {
+		const onRefresh = vi.fn();
+		render(<GatePanel {...baseProps} onRefresh={onRefresh} />);
+
+		await userEvent.click(
+			screen.getByRole("button", { name: "Refresh" }),
+		);
+		expect(onRefresh).toHaveBeenCalledOnce();
+	});
+
+	it("disables Refresh button when loading", () => {
+		render(<GatePanel {...baseProps} isGateLoading={true} />);
+		expect(screen.getByRole("button", { name: "Refresh" })).toBeDisabled();
+	});
+});

frontend/src/components/ReviewPanel.test.tsx

@@ -0,0 +1,157 @@
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, expect, it, vi } from "vitest";
+import type { ReviewStory } from "../api/workflow";
+import { ReviewPanel } from "./ReviewPanel";
+
+const readyStory: ReviewStory = {
+	story_id: "29_backfill_tests",
+	can_accept: true,
+	reasons: [],
+	warning: null,
+	summary: { total: 5, passed: 5, failed: 0 },
+	missing_categories: [],
+};
+
+const blockedStory: ReviewStory = {
+	story_id: "26_tdd_gates",
+	can_accept: false,
+	reasons: ["2 tests are failing."],
+	warning: "Multiple tests failing — fix one at a time.",
+	summary: { total: 5, passed: 3, failed: 2 },
+	missing_categories: [],
+};
+
+const baseProps = {
+	reviewQueue: [] as ReviewStory[],
+	isReviewLoading: false,
+	reviewError: null,
+	proceedingStoryId: null,
+	storyId: "",
+	isGateLoading: false,
+	proceedError: null,
+	proceedSuccess: null,
+	lastReviewRefresh: null,
+	onRefresh: vi.fn(),
+	onProceed: vi.fn().mockResolvedValue(undefined),
+};
+
+describe("ReviewPanel", () => {
+	it("shows empty state when no stories", () => {
+		render(<ReviewPanel {...baseProps} />);
+		expect(
+			screen.getByText("No stories waiting for review."),
+		).toBeInTheDocument();
+	});
+
+	it("shows loading state", () => {
+		render(<ReviewPanel {...baseProps} isReviewLoading={true} />);
+		expect(screen.getByText("Loading review queue...")).toBeInTheDocument();
+	});
+
+	it("shows error with retry button", async () => {
+		const onRefresh = vi.fn();
+		render(
+			<ReviewPanel
+				{...baseProps}
+				reviewError="Network error"
+				onRefresh={onRefresh}
+			/>,
+		);
+
+		expect(
+			screen.getByText(/Network error.*Use Refresh to try again\./),
+		).toBeInTheDocument();
+
+		await userEvent.click(screen.getByRole("button", { name: "Retry" }));
+		expect(onRefresh).toHaveBeenCalledOnce();
+	});
+
+	it("renders ready story with Proceed button", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[readyStory]} />);
+
+		expect(screen.getByText("29_backfill_tests")).toBeInTheDocument();
+		expect(screen.getByText("Ready")).toBeInTheDocument();
+		expect(screen.getByRole("button", { name: "Proceed" })).toBeEnabled();
+	});
+
+	it("renders blocked story with disabled button", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[blockedStory]} />);
+
+		expect(screen.getByText("26_tdd_gates")).toBeInTheDocument();
+		expect(screen.getAllByText("Blocked")).toHaveLength(2);
+		expect(screen.getByRole("button", { name: "Blocked" })).toBeDisabled();
+	});
+
+	it("shows failing badge with count", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[blockedStory]} />);
+		expect(screen.getByText("Failing 2")).toBeInTheDocument();
+	});
+
+	it("shows warning badge", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[blockedStory]} />);
+		expect(screen.getByText("Warning")).toBeInTheDocument();
+	});
+
+	it("shows test summary per story", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[readyStory]} />);
+		expect(screen.getByText(/5\/5 passing,\s*0 failing/)).toBeInTheDocument();
+	});
+
+	it("shows missing categories", () => {
+		const missingStory: ReviewStory = {
+			...blockedStory,
+			missing_categories: ["unit", "integration"],
+		};
+		render(<ReviewPanel {...baseProps} reviewQueue={[missingStory]} />);
+		expect(screen.getByText("Missing: unit, integration")).toBeInTheDocument();
+	});
+
+	it("calls onProceed when Proceed is clicked", async () => {
+		const onProceed = vi.fn().mockResolvedValue(undefined);
+		render(
+			<ReviewPanel
+				{...baseProps}
+				reviewQueue={[readyStory]}
+				onProceed={onProceed}
+			/>,
+		);
+
+		await userEvent.click(screen.getByRole("button", { name: "Proceed" }));
+		expect(onProceed).toHaveBeenCalledWith("29_backfill_tests");
+	});
+
+	it("shows queue counts in header", () => {
+		render(
+			<ReviewPanel {...baseProps} reviewQueue={[readyStory, blockedStory]} />,
+		);
+		expect(screen.getByText(/1 ready \/ 2 total/)).toBeInTheDocument();
+	});
+
+	it("shows proceedError message", () => {
+		render(
+			<ReviewPanel
+				{...baseProps}
+				proceedError="Acceptance blocked: tests failing"
+			/>,
+		);
+		expect(
+			screen.getByText("Acceptance blocked: tests failing"),
+		).toBeInTheDocument();
+	});
+
+	it("shows proceedSuccess message", () => {
+		render(
+			<ReviewPanel
+				{...baseProps}
+				proceedSuccess="Story accepted successfully"
+			/>,
+		);
+		expect(screen.getByText("Story accepted successfully")).toBeInTheDocument();
+	});
+
+	it("shows reasons as list items", () => {
+		render(<ReviewPanel {...baseProps} reviewQueue={[blockedStory]} />);
+		expect(screen.getByText("2 tests are failing.")).toBeInTheDocument();
+	});
+});

frontend/src/components/selection/usePathCompletion.test.ts

@@ -0,0 +1,160 @@
+import { act, renderHook, waitFor } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import type { FileEntry } from "./usePathCompletion";
+import {
+	getCurrentPartial,
+	isFuzzyMatch,
+	usePathCompletion,
+} from "./usePathCompletion";
+
+describe("isFuzzyMatch", () => {
+	it("matches when query is empty", () => {
+		expect(isFuzzyMatch("anything", "")).toBe(true);
+	});
+
+	it("matches exact prefix", () => {
+		expect(isFuzzyMatch("Documents", "Doc")).toBe(true);
+	});
+
+	it("matches fuzzy subsequence", () => {
+		expect(isFuzzyMatch("Documents", "dms")).toBe(true);
+	});
+
+	it("is case insensitive", () => {
+		expect(isFuzzyMatch("Documents", "DOCU")).toBe(true);
+	});
+
+	it("rejects when chars not found in order", () => {
+		expect(isFuzzyMatch("abc", "acb")).toBe(false);
+	});
+
+	it("rejects completely unrelated", () => {
+		expect(isFuzzyMatch("hello", "xyz")).toBe(false);
+	});
+});
+
+describe("getCurrentPartial", () => {
+	it("returns empty for empty input", () => {
+		expect(getCurrentPartial("")).toBe("");
+	});
+
+	it("returns empty when input ends with slash", () => {
+		expect(getCurrentPartial("/home/user/")).toBe("");
+	});
+
+	it("returns last segment", () => {
+		expect(getCurrentPartial("/home/user/Doc")).toBe("Doc");
+	});
+
+	it("returns full input when no slash", () => {
+		expect(getCurrentPartial("Doc")).toBe("Doc");
+	});
+
+	it("trims then evaluates: trailing-slash input returns empty", () => {
+		// "  /home/user/  " trims to "/home/user/" which ends with slash
+		expect(getCurrentPartial("  /home/user/  ")).toBe("");
+	});
+
+	it("trims then returns last segment", () => {
+		expect(getCurrentPartial("  /home/user/Doc  ")).toBe("Doc");
+	});
+});
+
+describe("usePathCompletion hook", () => {
+	const mockListDir = vi.fn<(path: string) => Promise<FileEntry[]>>();
+
+	beforeEach(() => {
+		mockListDir.mockReset();
+	});
+
+	it("returns empty matchList for empty input", async () => {
+		const { result } = renderHook(() =>
+			usePathCompletion({
+				pathInput: "",
+				setPathInput: vi.fn(),
+				homeDir: "/home/user",
+				listDirectoryAbsolute: mockListDir,
+				debounceMs: 0,
+			}),
+		);
+
+		// Allow effect + setTimeout(0) to fire
+		await waitFor(() => {
+			expect(mockListDir).not.toHaveBeenCalled();
+		});
+
+		expect(result.current.matchList).toEqual([]);
+	});
+
+	it("fetches directory listing and returns matches", async () => {
+		mockListDir.mockResolvedValue([
+			{ name: "Documents", kind: "dir" },
+			{ name: "Downloads", kind: "dir" },
+			{ name: ".bashrc", kind: "file" },
+		]);
+
+		const { result } = renderHook(() =>
+			usePathCompletion({
+				pathInput: "/home/user/",
+				setPathInput: vi.fn(),
+				homeDir: "/home/user",
+				listDirectoryAbsolute: mockListDir,
+				debounceMs: 0,
+			}),
+		);
+
+		await waitFor(() => {
+			expect(result.current.matchList.length).toBe(2);
+		});
+
+		expect(result.current.matchList[0].name).toBe("Documents");
+		expect(result.current.matchList[1].name).toBe("Downloads");
+		expect(result.current.matchList.every((m) => m.path.endsWith("/"))).toBe(
+			true,
+		);
+	});
+
+	it("filters by fuzzy match on partial input", async () => {
+		mockListDir.mockResolvedValue([
+			{ name: "Documents", kind: "dir" },
+			{ name: "Downloads", kind: "dir" },
+			{ name: "Desktop", kind: "dir" },
+		]);
+
+		const { result } = renderHook(() =>
+			usePathCompletion({
+				pathInput: "/home/user/Doc",
+				setPathInput: vi.fn(),
+				homeDir: "/home/user",
+				listDirectoryAbsolute: mockListDir,
+				debounceMs: 0,
+			}),
+		);
+
+		await waitFor(() => {
+			expect(result.current.matchList.length).toBe(1);
+		});
+
+		expect(result.current.matchList[0].name).toBe("Documents");
+	});
+
+	it("calls setPathInput when acceptMatch is invoked", () => {
+		const setPathInput = vi.fn();
+
+		const { result } = renderHook(() =>
+			usePathCompletion({
+				pathInput: "/home/",
+				setPathInput,
+				homeDir: "/home",
+				listDirectoryAbsolute: mockListDir,
+				debounceMs: 0,
+			}),
+		);
+
+		act(() => {
+			result.current.acceptMatch("/home/user/Documents/");
+		});
+
+		expect(setPathInput).toHaveBeenCalledWith("/home/user/Documents/");
+	});
+});

frontend/src/components/selection/usePathCompletion.ts

@@ -30,7 +30,7 @@ export interface UsePathCompletionResult {
 	closeSuggestions: () => void;
 }
 
-function isFuzzyMatch(candidate: string, query: string) {
+export function isFuzzyMatch(candidate: string, query: string) {
 	if (!query) return true;
 	const lowerCandidate = candidate.toLowerCase();
 	const lowerQuery = query.toLowerCase();
@@ -43,7 +43,7 @@ function isFuzzyMatch(candidate: string, query: string) {
 	return true;
 }
 
-function getCurrentPartial(input: string) {
+export function getCurrentPartial(input: string) {
 	const trimmed = input.trim();
 	if (!trimmed) return "";
 	if (trimmed.endsWith("/")) return "";