feat: implement getToolContext for plugins to enrich core tool responses

apps/mcp/src/__tests__/plugin-loader.test.ts

@@ -0,0 +1,198 @@
+import { describe, expect, it, vi } from "vitest";
+import { PluginRegistry } from "../plugin-loader.js";
+import type { PacaConfig } from "../types/index.js";
+
+const config: PacaConfig = {
+	apiKey: "test-key",
+	baseURL: "http://localhost:8080",
+};
+
+// ---------------------------------------------------------------------------
+// PluginRegistry.getToolContext
+// ---------------------------------------------------------------------------
+
+describe("PluginRegistry.getToolContext", () => {
+	it("returns an empty array when no plugin is loaded", async () => {
+		const registry = new PluginRegistry([]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([]);
+	});
+
+	it("never calls a plugin that didn't declare a hook for this toolId", async () => {
+		const getToolContext = vi.fn().mockResolvedValue("should not be called");
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.no-hook",
+				entry: { tools: [], handleToolCall: vi.fn(), getToolContext },
+				toolContextHooks: [], // implements the method but never declared it
+			},
+		]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([]);
+		expect(getToolContext).not.toHaveBeenCalled();
+	});
+
+	it("only calls plugins that declared a hook for the requested toolId", async () => {
+		const taskHook = vi.fn().mockResolvedValue("## GitHub\nBranch: feat/t1");
+		const sprintOnlyHook = vi.fn().mockResolvedValue("should not run for get_task");
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.github",
+				entry: { tools: [], handleToolCall: vi.fn(), getToolContext: taskHook },
+				toolContextHooks: ["get_task"],
+			},
+			{
+				pluginId: "com.paca.other",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: sprintOnlyHook,
+				},
+				toolContextHooks: ["list_sprints"],
+			},
+		]);
+
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([
+			{ pluginId: "com.paca.github", text: "## GitHub\nBranch: feat/t1" },
+		]);
+		expect(taskHook).toHaveBeenCalledTimes(1);
+		expect(sprintOnlyHook).not.toHaveBeenCalled();
+	});
+
+	it("collects text from every declared plugin that returns a non-empty section", async () => {
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.github",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: vi.fn().mockResolvedValue("## GitHub\nBranch: feat/t1"),
+				},
+				toolContextHooks: ["get_task"],
+			},
+			{
+				pluginId: "com.paca.checklist",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: vi.fn().mockResolvedValue("## Checklist\n- [ ] Item"),
+				},
+				toolContextHooks: ["get_task"],
+			},
+		]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([
+			{ pluginId: "com.paca.github", text: "## GitHub\nBranch: feat/t1" },
+			{ pluginId: "com.paca.checklist", text: "## Checklist\n- [ ] Item" },
+		]);
+	});
+
+	it("omits plugins that resolve to null (nothing to contribute)", async () => {
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.github",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: vi.fn().mockResolvedValue(null),
+				},
+				toolContextHooks: ["get_task"],
+			},
+		]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([]);
+	});
+
+	it("logs and contributes nothing when a declared plugin's module has no getToolContext", async () => {
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.mismatched",
+				entry: { tools: [], handleToolCall: vi.fn() }, // no getToolContext impl
+				toolContextHooks: ["get_task"], // but manifest declares it
+			},
+		]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([]);
+	});
+
+	it("swallows a throwing plugin without affecting the others", async () => {
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.broken",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: vi.fn().mockRejectedValue(new Error("boom")),
+				},
+				toolContextHooks: ["get_task"],
+			},
+			{
+				pluginId: "com.paca.bdd",
+				entry: {
+					tools: [],
+					handleToolCall: vi.fn(),
+					getToolContext: vi.fn().mockResolvedValue("## BDD\nScenario: X"),
+				},
+				toolContextHooks: ["get_task"],
+			},
+		]);
+		const sections = await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(sections).toEqual([
+			{ pluginId: "com.paca.bdd", text: "## BDD\nScenario: X" },
+		]);
+	});
+
+	it("passes toolId, args, and per-plugin context to getToolContext", async () => {
+		const getToolContext = vi.fn().mockResolvedValue("## GitHub\n...");
+		const registry = new PluginRegistry([
+			{
+				pluginId: "com.paca.github",
+				entry: { tools: [], handleToolCall: vi.fn(), getToolContext },
+				toolContextHooks: ["get_task"],
+			},
+		]);
+		await registry.getToolContext(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			config,
+		);
+		expect(getToolContext).toHaveBeenCalledWith(
+			"get_task",
+			{ projectId: "p1", taskId: "t1" },
+			{
+				pluginId: "com.paca.github",
+				baseURL: config.baseURL,
+				apiKey: config.apiKey,
+			},
+		);
+	});
+});

apps/mcp/src/__tests__/server.test.ts

@@ -0,0 +1,74 @@
+import { describe, expect, it } from "vitest";
+import type { PluginContextSection } from "../plugin-loader.js";
+import { mergePluginContext } from "../server.js";
+
+// ---------------------------------------------------------------------------
+// mergePluginContext
+// ---------------------------------------------------------------------------
+//
+// Regression coverage for the bug described in the getToolContext PR: a
+// plugin's contributed text was originally appended as a separate trailing
+// content block, which agents were observed treating as unrelated and
+// ignoring (e.g. calling github_list_task_branches right after get_task
+// despite the branch already being in a second block). The fix merges into
+// the last existing text block instead.
+
+describe("mergePluginContext", () => {
+	const section = (text: string, pluginId = "com.paca.github") =>
+		[{ pluginId, text }] satisfies PluginContextSection[];
+
+	it("merges a single section into the last text block", () => {
+		const result = {
+			content: [{ type: "text", text: "# Task: Fix login bug" }],
+		};
+		const merged = mergePluginContext(
+			result,
+			section("## GitHub\nBranch: feat/t1"),
+		);
+		expect(merged.content).toHaveLength(1);
+		expect(merged.content[0]).toEqual({
+			type: "text",
+			text: "# Task: Fix login bug\n\n## GitHub\nBranch: feat/t1",
+		});
+	});
+
+	it("joins multiple sections in the given order before merging", () => {
+		const result = { content: [{ type: "text", text: "# Task" }] };
+		const merged = mergePluginContext(result, [
+			{ pluginId: "com.paca.github", text: "## GitHub" },
+			{ pluginId: "com.paca.checklist", text: "## Checklist" },
+		]);
+		expect(merged.content[0].text).toBe("# Task\n\n## GitHub\n\n## Checklist");
+	});
+
+	it("appends a new text block when content is empty", () => {
+		const result = { content: [] };
+		const merged = mergePluginContext(result, section("## GitHub"));
+		expect(merged.content).toEqual([{ type: "text", text: "## GitHub" }]);
+	});
+
+	it("appends a new text block when the last block isn't type text", () => {
+		const result = {
+			content: [{ type: "image", data: "base64...", mimeType: "image/png" }],
+		};
+		const merged = mergePluginContext(result, section("## GitHub"));
+		expect(merged.content).toHaveLength(2);
+		expect(merged.content[1]).toEqual({ type: "text", text: "## GitHub" });
+	});
+
+	it("does not mutate the original result's content array", () => {
+		const originalContent = [{ type: "text", text: "# Task" }];
+		const result = { content: originalContent };
+		mergePluginContext(result, section("## GitHub"));
+		expect(originalContent).toEqual([{ type: "text", text: "# Task" }]);
+	});
+
+	it("preserves other fields on the result (e.g. isError: false)", () => {
+		const result = {
+			content: [{ type: "text", text: "# Task" }],
+			isError: false,
+		};
+		const merged = mergePluginContext(result, section("## GitHub"));
+		expect(merged.isError).toBe(false);
+	});
+});