refactor: 移除 context-mode，Chrome 快照改为直接返回

context-mode 的 ctx_execute 系工具以真实 shell 执行且权限为 allow，绕过了
bash 策略与 protectedWrites；其每轮注入、独立 MCP 子进程与 skills 也与组合包
提示词单一所有权冲突。大输出职责已由 pi-overflow（入口截断）与
pi-compaction（压力遮蔽）承担：
- 删除 context-mode 依赖、wrapper/过滤器、skills，以及 ctx_* 的权限、
  tools.jsonc、路由规则、tool-search 常驻与 4 个分组
- better-sqlite3@12 仅为 context-mode 传递依赖，随之移除根 allowScripts
- pi-chrome：按用户决定移除快照隐私规则与 .pi/chrome-context 临时文件机制，
  快照 JSON 直接作为工具结果返回、details 只留小型元数据，超长由 pi-overflow
  截断并用 overflow_query 提取；授权生命周期不变

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

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

tests/system-prompt.test.ts

@@ -29,10 +29,6 @@ import systemPromptExtension, {
 	getSystemPromptDumpPath,
 } from "../extensions/system-prompt.ts";
 import { guardExtensionApi } from "../extensions/prompt-guard.ts";
-import {
-	CONTEXT_MODE_ANCHOR_PREFIX,
-	filterContextModeMessages,
-} from "../extensions/context-mode-filter.ts";
 import { BUNDLE_GROUP_DEFINITIONS } from "../pi-tool-search/extensions/bundle-groups.ts";
 import { BUNDLE_TOOL_SEARCH_DEFAULTS } from "../pi-tool-search/extensions/config.ts";
 
@@ -164,7 +160,6 @@ test("prompt config carries no retired guidance phrasing", () => {
 		"read/grep",
 		"replace_text",
 		"Read/edit files",
-		"ctx_fetch_and_index then ctx_search",
 	];
 	for (const file of ["preamble.md", "tools.jsonc", "routing.jsonc"]) {
 		const source = readFileSync(join(promptConfigDir, file), "utf8");
@@ -267,8 +262,8 @@ test("bundled routing rules select the same guidance the retired tool-routing ex
 	assert.match(ssh, /only when the user explicitly names an imported host/);
 	assert.match(ssh, /command-local directory change/);
 
-	const chrome = renderRouting(routing.rules, ["chrome_snapshot", "ctx_execute_file"]);
-	assert.match(chrome, /immediately analyze the returned workspace-relative capture path/);
+	const chrome = renderRouting(routing.rules, ["chrome_snapshot", "overflow_query"]);
+	assert.match(chrome, /return the page snapshot JSON directly/);
 
 	const minimal = renderRouting(routing.rules, ["read"]);
 	assert.doesNotMatch(minimal, /codegraph_explore first/);
@@ -646,7 +641,7 @@ test("prompt guard runs context results through the provided contextFilter", asy
 test("prompt guard returns the handler result untouched when the filter changes nothing", async () => {
 	const { pi, handlers } = makeRecordingPi();
 	const guarded = guardExtensionApi(pi as unknown as ExtensionAPI, {
-		contextFilter: filterContextModeMessages,
+		contextFilter: (_before, after) => after,
 	});
 	const expected = { messages: [{ role: "user", content: "plain" }] };
 
@@ -662,67 +657,6 @@ test("prompt guard passes unrelated API members through to the real pi object",
 	assert.equal((guarded as unknown as { someOtherApi: () => string }).someOtherApi(), "passthrough");
 });
 
-// ── context-mode filter ─────────────────────────────────────────────────────
-
-test("context-mode filter drops only the routing-anchor part", () => {
-	const before = [{ role: "user", content: "real" }];
-	const anchor = `${CONTEXT_MODE_ANCHOR_PREFIX} ctx_batch_execute > ctx_execute`;
-	const after = [
-		...before,
-		{ role: "user", content: `${anchor}\n\n<active_memory>\nx\n</active_memory>` },
-	];
-	const filtered = filterContextModeMessages(before, after);
-	assert.equal(filtered.length, 2);
-	assert.equal(filtered[1].content, "<active_memory>\nx\n</active_memory>");
-});
-
-test("context-mode filter removes the appended message when only the anchor remains", () => {
-	const before = [{ role: "user", content: "real" }];
-	const after = [
-		...before,
-		{ role: "user", content: `${CONTEXT_MODE_ANCHOR_PREFIX} only anchor` },
-	];
-	assert.deepEqual(filterContextModeMessages(before, after), before);
-});
-
-test("context-mode filter returns the same reference when nothing changed", () => {
-	const before = [{ role: "user", content: "real" }];
-	const after = [...before, { role: "user", content: "no anchor here" }];
-	assert.equal(filterContextModeMessages(before, after), after);
-	assert.equal(filterContextModeMessages(after, after), after);
-});
-
-test("context-mode filter ignores appended non-user or non-string messages", () => {
-	const before = [{ role: "user", content: "real" }];
-	const after = [
-		...before,
-		{ role: "assistant", content: `${CONTEXT_MODE_ANCHOR_PREFIX} not ours` },
-		{ role: "user", content: [{ type: "text", text: "structured" }] },
-	];
-	assert.equal(filterContextModeMessages(before, after), after);
-});
-
-// ── Pinned upstream text ────────────────────────────────────────────────────
-
-test("context-mode upstream still appends the single anchor-bearing user message", async () => {
-	const packageJson = JSON.parse(
-		await readFile(join(repositoryRoot, "package.json"), "utf8"),
-	) as { dependencies: Record<string, string> };
-	assert.match(
-		packageJson.dependencies["context-mode"] ?? "",
-		/^\d+\.\d+\.\d+$/,
-		"the context-filter pin requires an exact upstream version",
-	);
-	const upstream = await readFile(
-		join(repositoryRoot, "node_modules/context-mode/build/adapters/pi/extension.js"),
-		"utf8",
-	);
-	assert.ok(upstream.includes('parts.push("context-mode active. Hierarchy:'));
-	assert.ok(upstream.includes('_pendingContext = extraParts.join("\\n\\n")'));
-	assert.ok(upstream.includes("event.messages.push({"));
-	assert.ok(upstream.includes('role: "user"'));
-});
-
 // ── /dump-system-prompt ─────────────────────────────────────────────────────
 
 test("dump-system-prompt writes the last composed prompt under .pi-debug", async () => {