fix: MEMORY_FILE trim may discard DECREASED entries before 4c extraction (#875)

Address AI reviewer feedback on d1f75a7:

- Wrap cross_file append in try/except so a write failure never prevents
  the memory trim-write from running (bug fix)
- Stamp sweep_id on pre-trim exported entries using the SWEEP_ID env var;
  pass SWEEP_ID from red-team-sweep.sh so entries are attributable to a
  sweep run (data-consistency fix)
- Add inline comment explaining the 3-tuple dedup key (run, ts, strategy)
  and its relationship to step-4c's identity check (clarity nit)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/harb-evaluator/red-team-sweep.sh

@@ -116,7 +116,7 @@ PYEOF
   # 3. Run red-team.sh (handles bootstrap + compile + deploy + attack)
   log "Running red-team.sh (timeout: ${TIMEOUT_PER}s)..."
   set +e
-  CLAUDE_TIMEOUT="$TIMEOUT_PER" CANDIDATE_NAME="$seed_name" OPTIMIZER_PROFILE="$OPTIMIZER_PROFILE" \
+  CLAUDE_TIMEOUT="$TIMEOUT_PER" CANDIDATE_NAME="$seed_name" OPTIMIZER_PROFILE="$OPTIMIZER_PROFILE" SWEEP_ID="$SWEEP_ID" \
     timeout "$((TIMEOUT_PER + 120))" \
     bash "$SCRIPT_DIR/red-team.sh" 2>&1 | tee "/tmp/red-team-${seed_name}.log"
   RED_TEAM_EXIT="${PIPESTATUS[0]}"

scripts/harb-evaluator/red-team.sh

@@ -202,7 +202,7 @@ EOF
   fi
 
   python3 - "$stream_file" "$memory_file" "$run_num" "$LM_ETH_BEFORE" "$CANDIDATE_NAME" "$OPTIMIZER_PROFILE" "$CROSS_PATTERNS_FILE" <<'PYEOF'
-import json, sys, re
+import json, os, sys, re
 from datetime import datetime, timezone
 
 stream_file = sys.argv[1]
@@ -216,6 +216,7 @@ except (ValueError, IndexError):
 candidate = sys.argv[5] if len(sys.argv) > 5 else "unknown"
 optimizer_profile = sys.argv[6] if len(sys.argv) > 6 else "unknown"
 cross_file = sys.argv[7] if len(sys.argv) > 7 else None
+sweep_id = os.environ.get("SWEEP_ID", "unknown")
 
 def make_pattern(strategy_name, steps_text):
     """Extract abstract op sequence preserving execution order."""
@@ -377,6 +378,8 @@ if len(all_entries) > 50:
     seen = set()
     deduped = []
     for e in trimmed:
+        # 3-tuple key: run+ts uniquely identifies the extract_memory call; strategy
+        # distinguishes entries within the same call.  Matches step-4c's identity check.
         key = (e.get("run"), e.get("ts"), e.get("strategy"))
         if key not in seen:
             seen.add(key)
@@ -400,16 +403,20 @@ if len(all_entries) > 50:
                                 pass
             except FileNotFoundError:
                 pass
-            exported = 0
-            with open(cross_file, "a") as cf:
-                for e in dropped:
-                    key = (e.get("pattern", ""), e.get("candidate", ""), e.get("result", ""))
-                    if key not in existing_cross_keys:
-                        existing_cross_keys.add(key)
-                        cf.write(json.dumps(e) + "\n")
-                        exported += 1
-            if exported:
-                print(f"  Pre-trim export: {exported} dropped entr{'y' if exported == 1 else 'ies'} saved to cross-patterns")
+            try:
+                exported = 0
+                with open(cross_file, "a") as cf:
+                    for e in dropped:
+                        key = (e.get("pattern", ""), e.get("candidate", ""), e.get("result", ""))
+                        if key not in existing_cross_keys:
+                            existing_cross_keys.add(key)
+                            e.setdefault("sweep_id", sweep_id)
+                            cf.write(json.dumps(e) + "\n")
+                            exported += 1
+                if exported:
+                    print(f"  Pre-trim export: {exported} dropped entr{'y' if exported == 1 else 'ies'} saved to cross-patterns")
+            except Exception as ex:
+                print(f"  WARNING: pre-trim export failed: {ex}", file=sys.stderr)
 
     with open(memory_file, "w") as f:
         for e in deduped: