From 31d13ec6212e6f37cd006bcde79de78d266c4a63 Mon Sep 17 00:00:00 2001
From: roboomp <omp@can.ac>
Date: Sun, 14 Jun 2026 07:13:09 +0000
Subject: [PATCH] fix(coding-agent): skipped mixed-cwd legacy mnemopi banks

Only recall legacy mnemopi banks when every working_memory row is scoped to the active cwd, so per-project recall cannot surface sibling project rows from an ancestor-derived bank.

Fixes #2412
---
 packages/coding-agent/src/mnemopi/config.ts   | 23 +++++++++++--------
 .../test/mnemopi-bank-derivation.test.ts      | 10 +++++++-
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/packages/coding-agent/src/mnemopi/config.ts b/packages/coding-agent/src/mnemopi/config.ts
index 7c6b51647..a137b994e 100644
--- a/packages/coding-agent/src/mnemopi/config.ts
+++ b/packages/coding-agent/src/mnemopi/config.ts
@@ -172,10 +172,10 @@ function projectBankSegment(projectRoot: string): string {
 
 /**
  * Discover sibling banks under `<dbDir>/banks/` whose `working_memory` rows
- * already carry the active `cwd` in `metadata_json.$.cwd`, and add them to
- * the recall set. This rescues memories stranded by a previous, less-stable
- * bank derivation (#2412) without changing the write target — only recall is
- * widened.
+ * all carry the active `cwd` in `metadata_json.$.cwd`, and add those safe
+ * single-cwd banks to the recall set. This rescues memories stranded by a
+ * previous, less-stable bank derivation (#2412) without recalling mixed-cwd
+ * legacy banks wholesale under per-project isolation.
  *
  * Robust by design: a missing banks directory, unreadable bank dir, or
  * corrupt SQLite file is silently skipped. Scanning is capped at
@@ -202,19 +202,24 @@ export function extendRecallWithLegacyBanks(
 		if (scanned >= LEGACY_BANK_SCAN_LIMIT) break;
 		scanned++;
 		const candidate = path.join(banksDir, entry.name, "mnemopi.db");
-		if (bankHasCwd(candidate, cwdAbs)) extras.push(entry.name);
+		if (bankOnlyHasCwd(candidate, cwdAbs)) extras.push(entry.name);
 	}
 	return extras.length === 0 ? resolved : [...resolved, ...extras];
 }
 
-function bankHasCwd(dbPath: string, cwd: string): boolean {
+function bankOnlyHasCwd(dbPath: string, cwd: string): boolean {
 	let db: Database | undefined;
 	try {
 		db = new Database(dbPath, { readonly: true });
 		const row = db
-			.query("SELECT 1 FROM working_memory WHERE json_extract(metadata_json, '$.cwd') = ? LIMIT 1")
-			.get(cwd);
-		return row !== null;
+			.prepare<{ matching: number; unsafe: number }, [string, string]>(`
+				SELECT
+					SUM(CASE WHEN json_extract(metadata_json, '$.cwd') = ? THEN 1 ELSE 0 END) AS matching,
+					SUM(CASE WHEN json_extract(metadata_json, '$.cwd') IS NULL OR json_extract(metadata_json, '$.cwd') <> ? THEN 1 ELSE 0 END) AS unsafe
+				FROM working_memory
+			`)
+			.get(cwd, cwd);
+		return (row?.matching ?? 0) > 0 && (row?.unsafe ?? 0) === 0;
 	} catch (error) {
 		logger.debug("Mnemopi: legacy bank probe failed", { dbPath, error: String(error) });
 		return false;
diff --git a/packages/coding-agent/test/mnemopi-bank-derivation.test.ts b/packages/coding-agent/test/mnemopi-bank-derivation.test.ts
index 37695be5d..8bf16fcd1 100644
--- a/packages/coding-agent/test/mnemopi-bank-derivation.test.ts
+++ b/packages/coding-agent/test/mnemopi-bank-derivation.test.ts
@@ -100,7 +100,7 @@ describe("computeMnemopiBankScope (#2412)", () => {
 });
 
 describe("extendRecallWithLegacyBanks (#2412)", () => {
-	it("adds a sibling bank when working_memory rows tag the active cwd", () => {
+	it("adds a sibling bank only when all working_memory rows tag the active cwd", () => {
 		const activeCwd = "/home/user/projects/myrepo";
 		createBankFixture("legacy-A", [{ session_id: "old", cwd: activeCwd }]);
 		createBankFixture("unrelated-B", [{ session_id: "other", cwd: "/some/other/place" }]);
@@ -110,6 +110,14 @@ describe("extendRecallWithLegacyBanks (#2412)", () => {
 		expect(extended).not.toContain("unrelated-B");
 	});
 
+	it("skips mixed-cwd legacy banks because recall cannot filter rows by cwd", () => {
+		const activeCwd = "/home/user/projects/safe-child";
+		createBankFixture("mixed-cwd-legacy", [{ cwd: activeCwd }, { cwd: "/home/user/projects/sibling-child" }]);
+		const extended = extendRecallWithLegacyBanks(["active-bank"], mainDbPath, activeCwd);
+		expect(extended).toContain("active-bank");
+		expect(extended).not.toContain("mixed-cwd-legacy");
+	});
+
 	it("ignores banks already in the recall set", () => {
 		const cwd = "/home/user/projects/already-in-set";
 		createBankFixture("already-in-set", [{ cwd }]);