feat(TASK-023): deep-research hardening — fail-safe scripts, fault fallbacks, pipeline notes

R3 guards: parse_request (crash → ask_topic), bootstrap_research,
combine_findings (crash → fault-text findings; also lifts branch-local
PIPELINE-FAULT findings into pipeline_faults, deduped), reflexion_gate
(crash fails forward to synthesize), incorporate_feedback (crash still
loops with a generic feedback note), verify_sources (top-level guard +
pipeline_notes fold).

Fallbacks per the plan's naming pins: plan → plan_fault → end_fault
(fail-closed; gains state_updates plan_failure per the TASK-016 rule);
research_one_question → branch-local question_fault (map collects the
fault finding); vet_sources/critique → degrade-visibly markers that
continue to the stage each node's own next pointed to; synthesize →
synth_fault → end_fault. end_fault renders
'DEEP_RESEARCH FAILED — PIPELINE-FAULT: <fault text>'.

Accepted-path visibility: verify_sources folds pipeline_faults into
pipeline_notes ('' when fault-free), appended to end_accepted's output
and the approval question — happy-path output stays byte-identical.
initial_state seeds questions: [] so a dying plan inside the static
fan-out leaves the sibling knowledge_lookup lane mapping over zero
items while end_fault renders.

R5: 19 python3-guarded regression tests + GraphParser wiring test;
bundled warning baseline unchanged.

assets/agents/deep-research/scripts/combine_findings.py

@@ -6,6 +6,18 @@ one entry per sub-question, in input order). Downstream nodes
 (`vet_sources`, `critique`, `synthesize`) read `{{findings}}` as a
 single block, so this script renders the array as a Markdown document
 with one section per question.
+
+Fault visibility: a research lane that died lands here as a finding
+starting with "PIPELINE-FAULT:" (written by question_fault inside the map
+branch, where `pipeline_faults` itself is out of reach — map branches only
+surface their collected output_key). This script lifts such findings into
+`pipeline_faults` (deduplicated, since a reflexion or feedback loop can
+re-run the map) so dead lanes surface in the report's Pipeline notes.
+
+Fail-safe (R3): on a crash (e.g. malformed GRAPH_STATE), `findings`
+becomes the fault text itself and a PIPELINE-FAULT entry is recorded —
+the pipeline proceeds visibly degraded, and the human approval gate is
+the backstop. Existing faults are preserved best-effort.
 """
 import json
 import os
@@ -19,21 +31,40 @@ def load_state():
     return json.loads(os.environ.get("GRAPH_STATE", "{}"))
 
 
+def safe_faults():
+    try:
+        state = load_state()
+        return [f for f in (state.get("pipeline_faults") or []) if isinstance(f, str)]
+    except Exception:  # noqa: BLE001 — best-effort preservation only
+        return []
+
+
 def main():
     state = load_state()
     questions = state.get("questions") or []
     per_question = state.get("question_findings") or []
+    faults = [f for f in (state.get("pipeline_faults") or []) if isinstance(f, str)]
 
     sections = []
     for idx, q in enumerate(questions):
         body = per_question[idx] if idx < len(per_question) else ""
         if isinstance(body, dict) or isinstance(body, list):
             body = json.dumps(body, indent=2)
+        if isinstance(body, str) and body.startswith("PIPELINE-FAULT:") and body not in faults:
+            faults.append(body)
         sections.append(f"## {q}\n\n{body}")
 
     findings = "\n\n".join(sections) if sections else "No findings gathered."
-    print(json.dumps({"findings": findings}))
+    print(json.dumps({"findings": findings, "pipeline_faults": faults}))
 
 
-if __name__ == "__main__":
+try:
     main()
+except Exception as e:  # noqa: BLE001 — a crashed join must degrade, not die
+    faults = safe_faults()
+    fault = (
+        f"PIPELINE-FAULT: combining findings crashed — {e}; per-question "
+        "findings may exist in state but could not be joined"
+    )
+    faults.append(fault)
+    print(json.dumps({"findings": fault, "pipeline_faults": faults}))