Fix: UPDATE branch of upsert_entry dropped doc_refs + valid_until

The auditor's hybrid fixture (branch auditor/scaffold) surfaced this
on 2026-04-22. A re-seed of the same (operation, day) pair with new
endorsed_names merged the names but silently discarded the incoming
doc_refs and valid_until fields. schema_fingerprint was partially
handled (set-if-Some) but doc_refs and valid_until weren't touched.

Root cause: the UPDATE arm of upsert_entry at playbook_memory.rs:609
only covered:
  - endorsed_names (union-merge)
  - timestamp
  - embedding (if Some)
  - schema_fingerprint (if Some)

Fix:
  - valid_until — refresh if caller provides one
  - doc_refs — merge by tool (case-insensitive). Same-tool new entry
    supersedes older one; different-tool refs are appended. Empty
    incoming doc_refs preserves existing (don't wipe on partial seed).

4 new regression tests under upsert_tests:
  - update_merges_doc_refs_with_existing_ones
  - update_same_tool_supersedes_older_version
  - update_preserves_existing_doc_refs_when_new_entry_has_none
  - update_refreshes_valid_until_when_caller_provides_one

Test result: 9/9 upsert tests pass (4 new + 5 pre-existing).

Branch basis note: this branch is off main, so the UpsertOutcome enum
here still has the newtype variants Added(String) / Noop(String). PR
#2 (fix/upsert-outcome-serde) changes that enum to struct-like. When
PR #2 merges first this branch needs a trivial rebase; the UPDATE
arm logic is untouched by that change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/vectord/src/playbook_memory.rs

@@ -615,15 +615,45 @@ impl PlaybookMemory {
                     }
                     existing.endorsed_names = merged.clone();
                     existing.timestamp = new_entry.timestamp.clone();
-                    // Keep original playbook_id + embedding + schema fingerprint.
-                    // Refresh embedding only if the caller passed a non-None
-                    // one (indicates the text shape changed).
+                    // Keep original playbook_id. Refresh embedding only
+                    // if the caller passed a non-None one (indicates
+                    // the text shape changed).
                     if new_entry.embedding.is_some() {
                         existing.embedding = new_entry.embedding.clone();
                     }
+                    // Lifecycle / drift-signal fields — refresh only
+                    // when the caller provides a new value. Each was
+                    // previously either ignored entirely (valid_until,
+                    // doc_refs) or only partially handled. Caught by
+                    // the auditor's hybrid fixture on 2026-04-22 when
+                    // re-seeding with fresh doc_refs silently dropped
+                    // them on the UPDATE path.
                     if new_entry.schema_fingerprint.is_some() {
                         existing.schema_fingerprint = new_entry.schema_fingerprint.clone();
                     }
+                    if new_entry.valid_until.is_some() {
+                        existing.valid_until = new_entry.valid_until.clone();
+                    }
+                    if !new_entry.doc_refs.is_empty() {
+                        // Merge by tool (case-insensitive). A new ref
+                        // for the same tool supersedes the old one —
+                        // caller is asserting "this is what I used
+                        // now." Refs for tools the existing entry
+                        // didn't track are appended. This keeps the
+                        // cumulative tool history without letting a
+                        // single re-seed erase it.
+                        let mut merged_refs = existing.doc_refs.clone();
+                        for new_ref in &new_entry.doc_refs {
+                            let hit = merged_refs.iter().position(|r| {
+                                r.tool.eq_ignore_ascii_case(&new_ref.tool)
+                            });
+                            match hit {
+                                Some(idx) => merged_refs[idx] = new_ref.clone(),
+                                None => merged_refs.push(new_ref.clone()),
+                            }
+                        }
+                        existing.doc_refs = merged_refs;
+                    }
                     let pid = existing.playbook_id.clone();
                     drop(state);
                     self.persist().await?;
@@ -1662,6 +1692,117 @@ mod upsert_tests {
         assert!(matches!(o, UpsertOutcome::Added(_)));
         assert_eq!(pm.entry_count().await, 2);
     }
+
+    // Regression test for the auditor-discovered bug: UPDATE branch
+    // silently dropped doc_refs, valid_until, and (partially)
+    // schema_fingerprint from the incoming entry.
+    //
+    // Before the fix: a re-seed with different endorsed_names AND new
+    // doc_refs would merge names but discard the new doc_refs. After:
+    // both sets are unioned (doc_refs merged by tool, same-tool
+    // supersedes).
+
+    fn docref(tool: &str, version: &str) -> DocRef {
+        DocRef {
+            tool: tool.into(),
+            version_seen: version.into(),
+            snippet_hash: Some(format!("hash-{tool}-{version}")),
+            source_url: None,
+            seen_at: "2026-04-22T00:00:00Z".into(),
+        }
+    }
+
+    fn mk_with_docs(op: &str, day: &str, names: &[&str], docs: Vec<DocRef>) -> PlaybookEntry {
+        let mut e = mk(op, day, names);
+        e.doc_refs = docs;
+        e
+    }
+
+    #[tokio::test]
+    async fn update_merges_doc_refs_with_existing_ones() {
+        let pm = PlaybookMemory::new(Arc::new(InMemory::new()));
+        let day = "2026-04-22";
+        let op = "fill: Welder x2 in Nashville, TN";
+
+        // First seed: Alice + Docker doc ref
+        let e1 = mk_with_docs(op, day, &["Alice"], vec![docref("docker", "24.0.7")]);
+        let o1 = pm.upsert_entry(e1).await.unwrap();
+        assert!(matches!(o1, UpsertOutcome::Added(_)));
+
+        // Second seed on same (op, day) but new names AND new tool ref
+        let e2 = mk_with_docs(op, day, &["Bob"], vec![docref("terraform", "1.5.0")]);
+        let o2 = pm.upsert_entry(e2).await.unwrap();
+        assert!(matches!(o2, UpsertOutcome::Updated { .. }));
+        assert_eq!(pm.entry_count().await, 1); // still one entry, merged
+
+        let snap = pm.snapshot().await;
+        assert_eq!(snap.len(), 1);
+        let merged = &snap[0];
+        // Names unioned
+        assert!(merged.endorsed_names.contains(&"Alice".to_string()));
+        assert!(merged.endorsed_names.contains(&"Bob".to_string()));
+        // Both doc_refs preserved (different tools → union)
+        assert_eq!(merged.doc_refs.len(), 2);
+        let tools: Vec<_> = merged.doc_refs.iter().map(|r| r.tool.as_str()).collect();
+        assert!(tools.contains(&"docker"));
+        assert!(tools.contains(&"terraform"));
+    }
+
+    #[tokio::test]
+    async fn update_same_tool_supersedes_older_version() {
+        let pm = PlaybookMemory::new(Arc::new(InMemory::new()));
+        let day = "2026-04-22";
+        let op = "fill: Welder x2 in Nashville, TN";
+
+        let e1 = mk_with_docs(op, day, &["Alice"], vec![docref("docker", "24.0.7")]);
+        pm.upsert_entry(e1).await.unwrap();
+
+        // Same day, different name, SAME tool newer version
+        let e2 = mk_with_docs(op, day, &["Bob"], vec![docref("docker", "25.0.1")]);
+        let o2 = pm.upsert_entry(e2).await.unwrap();
+        assert!(matches!(o2, UpsertOutcome::Updated { .. }));
+
+        let snap = pm.snapshot().await;
+        assert_eq!(snap[0].doc_refs.len(), 1, "same tool should supersede, not duplicate");
+        assert_eq!(snap[0].doc_refs[0].version_seen, "25.0.1");
+    }
+
+    #[tokio::test]
+    async fn update_preserves_existing_doc_refs_when_new_entry_has_none() {
+        let pm = PlaybookMemory::new(Arc::new(InMemory::new()));
+        let day = "2026-04-22";
+        let op = "fill: Welder x2 in Nashville, TN";
+
+        let e1 = mk_with_docs(op, day, &["Alice"], vec![docref("docker", "24.0.7")]);
+        pm.upsert_entry(e1).await.unwrap();
+
+        // Second seed doesn't carry doc_refs — shouldn't wipe the existing
+        let e2 = mk(op, day, &["Bob"]); // no doc_refs
+        pm.upsert_entry(e2).await.unwrap();
+
+        let snap = pm.snapshot().await;
+        assert_eq!(snap[0].doc_refs.len(), 1, "empty new doc_refs shouldn't wipe existing");
+        assert_eq!(snap[0].doc_refs[0].tool, "docker");
+    }
+
+    #[tokio::test]
+    async fn update_refreshes_valid_until_when_caller_provides_one() {
+        let pm = PlaybookMemory::new(Arc::new(InMemory::new()));
+        let day = "2026-04-22";
+        let op = "fill: Welder x2 in Nashville, TN";
+
+        // First seed with no valid_until
+        let e1 = mk(op, day, &["Alice"]);
+        pm.upsert_entry(e1).await.unwrap();
+
+        // Second seed with a valid_until deadline
+        let mut e2 = mk(op, day, &["Bob"]);
+        e2.valid_until = Some("2026-05-01T00:00:00Z".into());
+        pm.upsert_entry(e2).await.unwrap();
+
+        let snap = pm.snapshot().await;
+        assert_eq!(snap[0].valid_until.as_deref(), Some("2026-05-01T00:00:00Z"));
+    }
 }
 
 #[cfg(test)]