From 3d0a72c58e5070e0729f32ea094ec51a5e39c4f7 Mon Sep 17 00:00:00 2001
From: Param Harrison <paramanantham@live.com>
Date: Sat, 31 Oct 2026 00:09:26 +0200
Subject: [PATCH] Pin the factory config at run start so a build cannot change
 the gate commands

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 factory/engine/cli.ts         |  2 ++
 factory/engine/models.test.ts | 18 +++++++++++++++++-
 factory/engine/portable.ts    |  7 +++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/factory/engine/cli.ts b/factory/engine/cli.ts
index 051ba72..4d7a1e5 100644
--- a/factory/engine/cli.ts
+++ b/factory/engine/cli.ts
@@ -4,6 +4,7 @@ import { join } from "node:path";
 import { loadConfig } from "../config.ts";
 import { runWorkflow } from "./interpret.ts";
 import { type Metrics, metricsFor, metricsSchema, rollup } from "./metrics.ts";
+import { pinPortable } from "./portable.ts";
 import { realHost } from "./real-host.ts";
 import { loadWorkflow } from "./workflow.ts";
 
@@ -12,6 +13,7 @@ const gh = (...a: string[]) => execFileSync("gh", a, { encoding: "utf8" });
 
 // Runs one issue through a named workflow on the current checkout and saves metrics.json.
 export async function runIssue(n: number, name: string) {
+  pinPortable();
   const wf = loadWorkflow(readFileSync(`.factory/workflows/${name}.yaml`, "utf8"));
   const issue = JSON.parse(gh("issue", "view", String(n), "--json", "title,body"));
   const base = execFileSync("git", ["merge-base", "HEAD", "origin/main"], {
diff --git a/factory/engine/models.test.ts b/factory/engine/models.test.ts
index 16debfc..82b146f 100644
--- a/factory/engine/models.test.ts
+++ b/factory/engine/models.test.ts
@@ -1,10 +1,13 @@
+import { mkdtempSync, readFileSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { describe, expect, it } from "vitest";
 import { loadConfig } from "../config.ts";
 import { badPlanLines } from "./artifacts.ts";
 import { fakeHost } from "./fake-host.ts";
 import { runWorkflow } from "./interpret.ts";
 import { resolveModel } from "./models.ts";
-import { globToRegExp, loadPortable } from "./portable.ts";
+import { globToRegExp, loadPortable, pinPortable, portable } from "./portable.ts";
 import { loadWorkflow } from "./workflow.ts";
 
 const cfg = loadConfig();
@@ -84,3 +87,16 @@ describe("portable config", () => {
     expect(globToRegExp("a/*.ts").test("a/b/c.ts")).toBe(false);
   });
 });
+
+describe("pinned portable config", () => {
+  it("keeps the commands it read at the start when the file changes later", () => {
+    const dir = mkdtempSync(join(tmpdir(), "pin-"));
+    const file = join(dir, "config.yaml");
+    const original = readFileSync(".factory/config.yaml", "utf8");
+    writeFileSync(file, original);
+    const pinned = pinPortable(file);
+    writeFileSync(file, original.replace(/gate:.*/, "gate: [true]"));
+    expect(portable().gate).toEqual(pinned.gate);
+    pinPortable();
+  });
+});
diff --git a/factory/engine/portable.ts b/factory/engine/portable.ts
index fb961de..d062b99 100644
--- a/factory/engine/portable.ts
+++ b/factory/engine/portable.ts
@@ -32,6 +32,13 @@ export const portable = (): Portable => {
   return cached;
 };
 
+// Called before the first agent runs, so a build that edits the file cannot change the commands
+// the gate runs: the working tree is never read for this again.
+export const pinPortable = (path?: string): Portable => {
+  cached = loadPortable(path);
+  return cached;
+};
+
 // ** crosses folders, * stays inside one.
 export function globToRegExp(glob: string): RegExp {
   const body = glob