From a033fdfb023de904d95f18ba7198564daac7e03a Mon Sep 17 00:00:00 2001
From: Jaden Earl <jadendwightearl@gmail.com>
Date: Thu, 2 Jul 2026 09:10:27 -0600
Subject: [PATCH] Record fetching backend per URL in run reports

Add a "backend" field to each entry in reports/<run_id>.json: the
fetcher recorded on the stored capture (set for stored/deduped/
cache_hit outcomes, "" when nothing was fetched, e.g. errors). This
lets downstream tooling attribute per-domain cost by backend without
changing the cost estimation itself.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../test_source_archive/test_reports.py       | 38 +++++++++++++++++++
 .../source_archive/reports.py                 | 14 ++++++-
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/code_tests/unit_tests/test_agents_and_tools/test_source_archive/test_reports.py b/code_tests/unit_tests/test_agents_and_tools/test_source_archive/test_reports.py
index a3248fa8..52c9d841 100644
--- a/code_tests/unit_tests/test_agents_and_tools/test_source_archive/test_reports.py
+++ b/code_tests/unit_tests/test_agents_and_tools/test_source_archive/test_reports.py
@@ -1,6 +1,12 @@
 from __future__ import annotations
 
+import json
+
 from forecasting_tools.agents_and_tools.source_archive.config import ArchiveConfig
+from forecasting_tools.agents_and_tools.source_archive.models import (
+    StoredCapture,
+    url_hash,
+)
 from forecasting_tools.agents_and_tools.source_archive.pipeline import (
     CaptureOutcome,
     PipelineSummary,
@@ -12,6 +18,12 @@
 from forecasting_tools.agents_and_tools.source_archive.storage import LocalBlobStore
 
 
+def _stored(url: str, fetcher: str) -> StoredCapture:
+    return StoredCapture(
+        url=url, url_hash=url_hash(url), content_hash="c1", fetcher=fetcher
+    )
+
+
 def test_run_report_roundtrip_canonicalizes(tmp_path):
     store = LocalBlobStore(tmp_path)
     config = ArchiveConfig(s3_prefix="t")
@@ -29,6 +41,32 @@ def test_run_report_roundtrip_canonicalizes(tmp_path):
     assert out["https://b.test/q"] == "error"
 
 
+def test_run_report_records_backend_per_url(tmp_path):
+    store = LocalBlobStore(tmp_path)
+    config = ArchiveConfig(s3_prefix="t")
+    summary = PipelineSummary(
+        outcomes=[
+            CaptureOutcome(
+                url="https://a.test/p",
+                status="stored",
+                stored=_stored("https://a.test/p", "firecrawl"),
+            ),
+            CaptureOutcome(
+                url="https://c.test/r",
+                status="cache_hit",
+                stored=_stored("https://c.test/r", "playwright"),
+            ),
+            CaptureOutcome(url="https://b.test/q", status="error", reason="cloudflare"),
+        ]
+    )
+    key = write_run_report(store, "r1", summary, config)
+
+    rows = {r["url"]: r for r in json.loads(store.get(key).decode("utf-8"))}
+    assert rows["https://a.test/p"]["backend"] == "firecrawl"
+    assert rows["https://c.test/r"]["backend"] == "playwright"
+    assert rows["https://b.test/q"]["backend"] == ""  # nothing fetched
+
+
 def test_captured_status_wins_over_failure(tmp_path):
     store = LocalBlobStore(tmp_path)
     config = ArchiveConfig(s3_prefix="t")
diff --git a/forecasting_tools/agents_and_tools/source_archive/reports.py b/forecasting_tools/agents_and_tools/source_archive/reports.py
index ba75b4b6..37e8a2cd 100644
--- a/forecasting_tools/agents_and_tools/source_archive/reports.py
+++ b/forecasting_tools/agents_and_tools/source_archive/reports.py
@@ -35,9 +35,19 @@ def report_key(run_id: str, config: ArchiveConfig) -> str:
 def write_run_report(
     store: BlobStore, run_id: str, summary, config: ArchiveConfig
 ) -> str:
-    """Persist a run's per-URL outcomes; ``summary`` is a ``PipelineSummary``."""
+    """Persist a run's per-URL outcomes; ``summary`` is a ``PipelineSummary``.
+
+    ``backend`` is the fetcher that produced the capture (from the stored
+    capture, so it is set for stored/deduped/cache_hit outcomes and ``""``
+    when unknown, e.g. errors) — it enables per-domain cost attribution.
+    """
     rows = [
-        {"url": o.url, "status": o.status, "reason": getattr(o, "reason", "")}
+        {
+            "url": o.url,
+            "status": o.status,
+            "reason": getattr(o, "reason", ""),
+            "backend": o.stored.fetcher if o.stored is not None else "",
+        }
         for o in summary.outcomes
     ]
     key = report_key(run_id, config)