feat(prompt): 重新注册 bash，把"不要用 bash 搜索"写进工具描述

真实会话里模型仍习惯性先调 bash grep，被拒后才改用 grep 工具；系统提示词里已有 4 处
提醒，但模型下调用决定时看的是工具 schema 描述，而 Pi 内置 bash 描述对此只字未提。

- 新增 extensions/bash-override.ts：用 Pi 的 createBashToolDefinition 重新注册 bash，
  执行、输出结构与 codemode 说明完全沿用上游；shellPath/commandPrefix 按 ctx.cwd
  经 SettingsManager 惰性解析，与内置一致
- tools.jsonc 新增 descriptionAppend 字段，由 prompt-guard 注册时拼接到上游描述后
- bash 增加命令→工具对照规则（grep -n / grep -rl / find -name），并提示
  文件清单用 $(git ls-files) 传参、不要接 xargs（会触发权限审核）

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/extension-load.test.ts

@@ -58,6 +58,11 @@ test("all package extensions load together without global registration conflicts
 		packageJson.pi.extensions.includes("./extensions/codegraph.ts"),
 		"the bundle must expose the native codegraph_explore tool",
 	);
+	assert.equal(
+		packageJson.pi.extensions.indexOf("./extensions/bash-override.ts"),
+		packageJson.pi.extensions.indexOf("./extensions/fff-override.ts") + 1,
+		"the bash description override must register right after fff-override",
+	);
 	assert.ok(
 		packageJson.pi.extensions.includes("./pi-web-search/index.ts"),
 		"the bundle must load the unified pi-web-search tools",
@@ -292,21 +297,51 @@ test("all package extensions load together without global registration conflicts
 	const home = await mkdtemp(join(tmpdir(), "my-pi-extension-load-"));
 	const mockBin = join(home, "bin");
 	await mkdir(mockBin, { recursive: true });
-	// Probe loaded LAST: records every registered tool (name + exposure) and the
-	// final active set so the test can assert the pinned built-in codemode.
+	// Probe loaded LAST: records every registered tool (name, exposure,
+	// description, source) and the final active set so the test can assert the
+	// pinned built-in codemode. Its async setup also runs the bash override's
+	// registered definition end to end — executing `echo hi` through the same
+	// delegation path a model call would use.
 	const probeOutput = join(home, "probe-tools.json");
 	const probePath = join(home, "probe.ts");
 	await writeFile(
 		probePath,
 		[
 			'import { writeFileSync } from "node:fs";',
-			"export default function (pi: any): void {",
+			`import bashOverrideExtension from ${JSON.stringify(join(repositoryRoot, "extensions", "bash-override.ts"))};`,
+			"export default async function (pi: any): Promise<void> {",
+			"\tlet executed: unknown;",
+			"\ttry {",
+			"\t\tlet registered: any;",
+			"\t\tbashOverrideExtension({ registerTool: (tool: any) => { registered = tool; } } as any);",
+			"\t\tconst result = await registered.execute(",
+			'\t\t\t"probe-1",',
+			'\t\t\t{ command: "echo hi" },',
+			"\t\t\tundefined,",
+			"\t\t\tundefined,",
+			`\t\t\t{ cwd: ${JSON.stringify(home)}, sessionManager: { getSessionId: () => "probe-session", getSessionFile: () => undefined } } as any,`,
+			"\t\t);",
+			"\t\texecuted = {",
+			"\t\t\ttext: result?.content?.[0]?.text,",
+			"\t\t\texitCode: result?.structuredContent?.exit_code,",
+			"\t\t\thasOutputSchema: result?.structuredContent !== undefined,",
+			"\t\t\tregisteredDescription: registered?.description,",
+			"\t\t};",
+			"\t} catch (error) {",
+			"\t\texecuted = { error: String(error) };",
+			"\t}",
 			'\tpi.on("session_start", () => {',
 			"\t\twriteFileSync(",
 			`\t\t\t${JSON.stringify(probeOutput)},`,
 			"\t\t\tJSON.stringify({",
-			"\t\t\t\tall: pi.getAllTools().map((tool: any) => ({ name: tool.name, exposure: tool.exposure })),",
+			"\t\t\t\tall: pi.getAllTools().map((tool: any) => ({",
+			"\t\t\t\t\tname: tool.name,",
+			"\t\t\t\t\texposure: tool.exposure,",
+			"\t\t\t\t\tdescription: tool.description,",
+			"\t\t\t\t\tsourcePath: tool.sourceInfo?.path,",
+			"\t\t\t\t})),",
 			"\t\t\t\tactive: pi.getActiveTools(),",
+			"\t\t\t\texecuted,",
 			"\t\t\t}),",
 			"\t\t);",
 			"\t});",
@@ -337,8 +372,15 @@ test("all package extensions load together without global registration conflicts
 	assert.doesNotMatch(`${result.stdout}\n${result.stderr}`, /Failed to load extension|conflicts with/u);
 
 	const probe = JSON.parse(await readFile(probeOutput, "utf8")) as {
-		all: { name: string; exposure?: string }[];
+		all: { name: string; exposure?: string; description?: string; sourcePath?: string }[];
 		active: string[];
+		executed?: {
+			text?: string;
+			exitCode?: number;
+			hasOutputSchema?: boolean;
+			registeredDescription?: string;
+			error?: string;
+		};
 	};
 	const codemode = probe.all.find((tool) => tool.name === "codemode");
 	assert.equal(codemode?.exposure, "model-only", "Pi's built-in codemode must load with model-only exposure");
@@ -351,4 +393,31 @@ test("all package extensions load together without global registration conflicts
 		!probe.active.includes("multi_grep"),
 		"multi_grep must not appear in the active tool set",
 	);
+	const bash = probe.all.find((tool) => tool.name === "bash");
+	assert.ok(bash, "the bundle must expose the bash tool");
+	assert.ok(
+		bash.description?.startsWith("Execute a bash command in the current working directory."),
+		"the bash override must keep Pi's upstream description prefix",
+	);
+	assert.ok(
+		bash.description?.endsWith("which triggers a permission review."),
+		"the registered bash description must end with the tools.jsonc descriptionAppend",
+	);
+	assert.ok(
+		(bash.sourcePath ?? "").endsWith("extensions/bash-override.ts"),
+		`bash must be registered by extensions/bash-override.ts, got ${bash.sourcePath}`,
+	);
+	const executed = probe.executed ?? {};
+	assert.equal(executed.error, undefined, `bash override execute must not throw: ${executed.error}`);
+	assert.equal(executed.exitCode, 0, "echo hi must exit 0 through the delegated definition");
+	assert.match(executed.text ?? "", /hi/);
+	assert.equal(
+		executed.hasOutputSchema,
+		true,
+		"the bash override must keep the upstream outputSchema (structuredContent for codemode)",
+	);
+	assert.ok(
+		executed.registeredDescription?.includes("Not for searching files"),
+		"the catalog descriptionAppend must reach the registered bash description",
+	);
 });