v1.12 track B.2: codecontext tool wrappers + tests

apps/server/src/services/codecontext_client.ts

@@ -0,0 +1,118 @@
+// v1.12 Track B.2: shared HTTP client for the codecontext sidecar. The 8
+// per-tool wrappers under tools/codecontext/ all funnel through callCodecontext
+// — they're thin adapters that supply toolName + args + projectPath. The
+// client owns:
+//
+//   1. target_dir validation. Codecontext's HTTP shim is naive and forwards
+//      any target_dir to codecontext, so without this layer a model that
+//      hallucinated a target_dir could read /opt/anything-on-disk. The
+//      project root is realpath'd and the requested target_dir is constrained
+//      to it (same invariant as path_guard.ts but for the codecontext path).
+//   2. Inline truncation at 32 kB. Codecontext outputs are markdown reports
+//      that can balloon on large projects; the model can re-narrow via
+//      file_path / file_type / limit. Matches the "inline truncation, no
+//      opaque-id retrieval" decision locked in the 2026-05-21 recon.
+//   3. Friendly mapping of codecontext's known failure modes — the empty-
+//      file parser bug (upstream issue #37) returns a generic error string,
+//      which we re-surface with a hint to add the file to .codecontextignore.
+
+import { realpath } from 'node:fs/promises';
+
+export interface CodecontextRequest {
+  toolName: string;
+  args: Record<string, unknown>;
+  projectPath: string;
+}
+
+export interface CodecontextResponse {
+  result: string;
+  truncated: boolean;
+}
+
+const CODECONTEXT_BASE_URL = process.env['CODECONTEXT_URL'] ?? 'http://codecontext:8080';
+const TRUNCATION_LIMIT = 32_000;
+const REQUEST_TIMEOUT_MS = 30_000;
+
+export async function callCodecontext(
+  req: CodecontextRequest,
+  fetcher: typeof fetch = fetch,
+): Promise<CodecontextResponse> {
+  // Step 1: realpath the project root, then realpath the requested target_dir
+  // (defaulting to projectPath when the caller didn't pass one — the 8 wrappers
+  // never pass target_dir; tests can override). A non-existent target_dir
+  // throws before we hit the network so the model gets a sharp error.
+  const resolvedProject = await realpath(req.projectPath);
+  const requestedTarget = req.args['target_dir'];
+  const targetDir = typeof requestedTarget === 'string' && requestedTarget.length > 0
+    ? requestedTarget
+    : req.projectPath;
+  const resolvedTarget = await realpath(targetDir).catch(() => null);
+  if (resolvedTarget === null) {
+    throw new Error(`target_dir does not exist: ${targetDir}`);
+  }
+  if (resolvedTarget !== resolvedProject && !resolvedTarget.startsWith(resolvedProject + '/')) {
+    throw new Error(`target_dir ${targetDir} escapes project root ${resolvedProject}`);
+  }
+
+  // Step 2: re-build args with the resolved target_dir so codecontext sees
+  // the real absolute path, not a symlink or relative form.
+  const argsToSend = { ...req.args, target_dir: resolvedTarget };
+
+  // Step 3: POST with a hard timeout. AbortController + setTimeout pattern
+  // matches web_fetch.ts; nothing fancier needed.
+  const controller = new AbortController();
+  const timer = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
+  let response: Response;
+  try {
+    response = await fetcher(`${CODECONTEXT_BASE_URL}/v1/${req.toolName}`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(argsToSend),
+      signal: controller.signal,
+    });
+  } catch (err) {
+    clearTimeout(timer);
+    if (err instanceof Error && (err.name === 'AbortError' || err.name === 'TimeoutError')) {
+      throw new Error(`codecontext request timed out after ${REQUEST_TIMEOUT_MS}ms`);
+    }
+    throw new Error(
+      `codecontext network error: ${err instanceof Error ? err.message : String(err)}`,
+    );
+  }
+  clearTimeout(timer);
+
+  if (!response.ok) {
+    const text = await response.text().catch(() => '');
+    throw new Error(`codecontext HTTP ${response.status}: ${text.slice(0, 200)}`);
+  }
+
+  const body = (await response.json()) as { result: string | null; error: string | null };
+  if (body.error) {
+    // Upstream issue #37: empty source files crash codecontext's parser. The
+    // error message reliably contains "content is empty"; surface an
+    // actionable hint instead of the bare codecontext message.
+    if (body.error.includes('content is empty')) {
+      throw new Error(
+        `codecontext parse failure: ${body.error}. ` +
+          `Add the offending path to .codecontextignore in the project root and retry.`,
+      );
+    }
+    throw new Error(`codecontext error: ${body.error}`);
+  }
+  if (body.result === null) {
+    return { result: '', truncated: false };
+  }
+
+  // Step 4: inline truncation. The model gets a clear hint about how to
+  // narrow the next call rather than a silent cut. Mirrors web_fetch.ts.
+  if (body.result.length > TRUNCATION_LIMIT) {
+    const truncated = body.result.slice(0, TRUNCATION_LIMIT);
+    const omitted = body.result.length - TRUNCATION_LIMIT;
+    return {
+      result:
+        `${truncated}\n\n[truncated, ${omitted} chars omitted; narrow with file_path, file_type, or limit]`,
+      truncated: true,
+    };
+  }
+  return { result: body.result, truncated: false };
+}