diff --git a/.changeset/fix-session-timeout.md b/.changeset/fix-session-timeout.md
new file mode 100644
index 0000000..eed2bb8
--- /dev/null
+++ b/.changeset/fix-session-timeout.md
@@ -0,0 +1,11 @@
+---
+"@vndv/pi-codegraph": patch
+---
+
+Make MCP session timeout configurable via `CODEGRAPH_TIMEOUT_MS` environment variable
+
+The default timeout has been increased from 20s to 60s to accommodate larger projects where `codegraph serve --mcp` cold start exceeds the previous limit. Users can override via:
+
+```bash
+export CODEGRAPH_TIMEOUT_MS=90000  # 90 seconds
+```
diff --git a/__tests__/codegraph.test.ts b/__tests__/codegraph.test.ts
index fd3bd60..0c0114b 100644
--- a/__tests__/codegraph.test.ts
+++ b/__tests__/codegraph.test.ts
@@ -286,6 +286,9 @@ describe("pi-codegraph extension", () => {
 
   it("times out when the MCP session never completes", async () => {
     const { spawn } = await import("node:child_process");
+    const originalEnv = process.env.CODEGRAPH_TIMEOUT_MS;
+    process.env.CODEGRAPH_TIMEOUT_MS = "20000";
+    vi.resetModules();
     const { withCodeGraphMcp, SessionTimeoutMs } = await import("../extensions/codegraph.js");
 
     const killMock = vi.fn(() => {});
@@ -303,6 +306,8 @@ describe("pi-codegraph extension", () => {
 
     await expect(promise).rejects.toThrow("CodeGraph MCP session timed out after " + SessionTimeoutMs);
     expect(killMock).toHaveBeenCalled();
+    if (originalEnv === undefined) delete process.env.CODEGRAPH_TIMEOUT_MS;
+    else process.env.CODEGRAPH_TIMEOUT_MS = originalEnv;
   }, 22000);
 
   it("normalizes codegraph_files path before forwarding to the MCP server", async () => {
diff --git a/extensions/codegraph.ts b/extensions/codegraph.ts
index 27b6c60..792a775 100644
--- a/extensions/codegraph.ts
+++ b/extensions/codegraph.ts
@@ -121,7 +121,14 @@ type PendingJsonRpcRequests = Map<number, {
 }>;
 
 export const MaxDiagnosticLength = 1000;
-export const SessionTimeoutMs = 20_000;
+export const SessionTimeoutMs = (() => {
+  const envValue = process.env.CODEGRAPH_TIMEOUT_MS;
+  if (envValue !== undefined) {
+    const parsed = parseInt(envValue, 10);
+    if (!Number.isNaN(parsed) && parsed > 0) return parsed;
+  }
+  return 60_000;
+})();
 
 export const codegraphToolNames = ToolDefinitions.map((tool) => tool.name);
 
diff --git a/package-lock.json b/package-lock.json
index 6a16189..1fa0604 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -911,7 +911,7 @@
         "typebox": "1.1.38"
       },
       "bin": {
-        "pi-ai": "./dist/cli.js"
+        "pi-ai": "dist/cli.js"
       },
       "engines": {
         "node": ">=22.19.0"