From 860237da784dd026be7c5f80b5af402c40d9ded5 Mon Sep 17 00:00:00 2001
From: Dustin Healy <54083382+dustinhealy@users.noreply.github.com>
Date: Sun, 7 Jun 2026 17:48:07 -0700
Subject: [PATCH] =?UTF-8?q?=F0=9F=94=8D=20fix:=20silent-mode=20collector?=
 =?UTF-8?q?=20+=20real=20layering=20test=20coverage?=
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- messagePiiFilter.ts: skip collector.matches.push in silent mode
  (no consumer reads it; small but pointless allocation per match).
  Also unifies the redaction log line so silent and warn both record
  what matched, just at debug-ish info level. Silent's contract is
  "no UI feedback," not "no server-side observability."

- messagePiiFilter.spec.ts: the previous "layers customPatterns on top
  of starters" test passed starterPatterns: [], which meant only the
  custom pattern ever fired; the test name lied. Renamed to
  "uses customPatterns only when starterPatterns is empty" and added
  a real layering test that exercises both a starter (sk_prefix) and
  a custom (acme) hitting the same prompt; asserts both ids land in
  collector.matches and both prefixes appear in the rewritten prompt.

- Silent-mode test updated to assert collector.matches is empty
  (was asserting length 1; corrected to match the new behavior).
---
 .../agents/__tests__/messagePiiFilter.spec.ts | 25 ++++++++++++++++---
 packages/api/src/agents/messagePiiFilter.ts   | 16 ++++++------
 2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/packages/api/src/agents/__tests__/messagePiiFilter.spec.ts b/packages/api/src/agents/__tests__/messagePiiFilter.spec.ts
index dadecde599..d8a6ae7030 100644
--- a/packages/api/src/agents/__tests__/messagePiiFilter.spec.ts
+++ b/packages/api/src/agents/__tests__/messagePiiFilter.spec.ts
@@ -47,7 +47,8 @@ describe('createMessagePiiFilterHooks', () => {
 
       expect(result.updatedPrompt).toBe('key sk-[REDACTED] please');
       expect(result.decision).toBeUndefined();
-      expect(built!.collector.matches).toHaveLength(1);
+      // Silent mode skips collector population (no consumer reads it)
+      expect(built!.collector.matches).toEqual([]);
     });
 
     it('is a no-op when nothing matches', async () => {
@@ -110,7 +111,7 @@ describe('createMessagePiiFilterHooks', () => {
       expect(result.updatedPrompt).toBe('auth Bearer [REDACTED] and key sk-ant-1234567890ABC');
     });
 
-    it('layers customPatterns on top of starters', async () => {
+    it('uses customPatterns only when starterPatterns is empty', async () => {
       const built = createMessagePiiFilterHooks(
         silent({
           starterPatterns: [],
@@ -123,7 +124,25 @@ describe('createMessagePiiFilterHooks', () => {
       });
 
       expect(result.updatedPrompt).toBe('token [REDACTED] ok');
-      expect(built!.collector.matches.map((m) => m.patternId)).toEqual(['acme']);
+    });
+
+    it('layers customPatterns on top of starters (both fire in one prompt)', async () => {
+      const built = createMessagePiiFilterHooks(
+        silent({
+          onMatch: 'warn',
+          customPatterns: [{ id: 'acme', label: 'Acme token', regex: '\\bACME-[A-Z0-9]{6,}' }],
+        }),
+      );
+      const result = await executeHooks({
+        registry: built!.registry,
+        input: promptInput('starter sk-anything-here and custom ACME-DEADBEEF12'),
+      });
+
+      const ids = built!.collector.matches.map((m) => m.patternId).sort();
+      expect(ids).toContain('sk_prefix');
+      expect(ids).toContain('acme');
+      expect(result.updatedPrompt).toContain('sk-[REDACTED]');
+      expect(result.updatedPrompt).toContain('[REDACTED]');
     });
 
     it('honors a custom redactionText', async () => {
diff --git a/packages/api/src/agents/messagePiiFilter.ts b/packages/api/src/agents/messagePiiFilter.ts
index 9879c4e3fd..71919038c7 100644
--- a/packages/api/src/agents/messagePiiFilter.ts
+++ b/packages/api/src/agents/messagePiiFilter.ts
@@ -91,7 +91,9 @@ export function createMessagePiiFilterHooks(
           return {};
         }
 
-        collector.matches.push(...matches);
+        if (mode !== 'silent') {
+          collector.matches.push(...matches);
+        }
 
         if (mode === 'block') {
           logger.info(
@@ -108,13 +110,11 @@ export function createMessagePiiFilterHooks(
         // silent + warn both redact server-side. The difference is
         // that warn surfaces the matches to the UI via the controller
         // (which reads collector.matches after processStream resolves).
-        if (mode === 'warn') {
-          logger.info(
-            `[messagePiiFilter] redacted ${matches.length} match(es) (mode=warn, patterns=${matches
-              .map((m) => m.patternId)
-              .join(',')})`,
-          );
-        }
+        logger.info(
+          `[messagePiiFilter] redacted ${matches.length} match(es) (mode=${mode}, patterns=${matches
+            .map((m) => m.patternId)
+            .join(',')})`,
+        );
 
         return { updatedPrompt: text };
       },