epimetheus: fix eval crash + wire per-PR cost tracking

Three bugs fixed:
1. triage_pr() returns 3 values but line 611 unpacked 2 → ValueError on every
   non-deterministic PR (circuit breaker opened, 5 PRs stuck)
2. costs import was inside triage else-block → NameError on deterministic routes
3. pr_cost never written to prs.cost_usd → 0% cost tracking across 1,118 PRs

Cost tracking now covers all 4 exit paths: domain failed, domain rejected,
Leo failed, and normal completion. Uses additive UPDATE (cost_usd + ?) so
re-evals accumulate correctly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ops/pipeline-v2/lib/evaluate.py

@@ -493,6 +493,9 @@ async def _dispose_rejected_pr(conn, pr_number: int, eval_attempts: int, all_iss
 
 async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
     """Evaluate a single PR. Returns result dict."""
+    from . import costs
+    pr_cost = 0.0
+
     # Check eval attempt budget before claiming
     row = conn.execute("SELECT eval_attempts FROM prs WHERE number = ?", (pr_number,)).fetchone()
     eval_attempts = (row["eval_attempts"] or 0) if row else 0
@@ -608,10 +611,8 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
                 json.dumps({"pr": pr_number, "tier": tier}),
             )
         else:
-            tier, triage_usage = await triage_pr(diff)
+            tier, triage_usage, _triage_reason = await triage_pr(diff)
-            # Record triage cost
+            pr_cost += costs.record_usage(
-            from . import costs
-            costs.record_usage(
                 conn, config.TRIAGE_MODEL, "eval_triage",
                 input_tokens=triage_usage.get("prompt_tokens", 0),
                 output_tokens=triage_usage.get("completion_tokens", 0),
@@ -674,6 +675,8 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
             # OpenRouter failure (timeout, error) — revert to open for retry.
             # NOT a rate limit — don't trigger 15-min backoff, just skip this PR.
             conn.execute("UPDATE prs SET status = 'open' WHERE number = ?", (pr_number,))
+            if pr_cost > 0:
+                conn.execute("UPDATE prs SET cost_usd = cost_usd + ? WHERE number = ?", (pr_cost, pr_number))
             return {"pr": pr_number, "skipped": True, "reason": "openrouter_failed"}
 
         domain_verdict = _parse_verdict(domain_review, agent)
@@ -714,6 +717,15 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
         # Disposition: check if this PR should be terminated or kept open
         await _dispose_rejected_pr(conn, pr_number, eval_attempts, domain_issues)
 
+        if domain_verdict != "skipped":
+            pr_cost += costs.record_usage(
+                conn, config.EVAL_DOMAIN_MODEL, "eval_domain",
+                input_tokens=domain_usage.get("prompt_tokens", 0),
+                output_tokens=domain_usage.get("completion_tokens", 0),
+                backend="openrouter",
+            )
+        if pr_cost > 0:
+            conn.execute("UPDATE prs SET cost_usd = cost_usd + ? WHERE number = ?", (pr_cost, pr_number))
         return {
             "pr": pr_number,
             "domain_verdict": domain_verdict,
@@ -731,6 +743,15 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
         if leo_review is None:
             # DEEP: Opus rate limited (queue for later). STANDARD: OpenRouter failed (skip, retry next cycle).
             conn.execute("UPDATE prs SET status = 'open' WHERE number = ?", (pr_number,))
+            if domain_verdict != "skipped":
+                pr_cost += costs.record_usage(
+                    conn, config.EVAL_DOMAIN_MODEL, "eval_domain",
+                    input_tokens=domain_usage.get("prompt_tokens", 0),
+                    output_tokens=domain_usage.get("completion_tokens", 0),
+                    backend="openrouter",
+                )
+            if pr_cost > 0:
+                conn.execute("UPDATE prs SET cost_usd = cost_usd + ? WHERE number = ?", (pr_cost, pr_number))
             reason = "opus_rate_limited" if tier == "DEEP" else "openrouter_failed"
             return {"pr": pr_number, "skipped": True, "reason": reason}
 
@@ -834,10 +855,8 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
         await _dispose_rejected_pr(conn, pr_number, eval_attempts, all_issues)
 
     # Record cost (only for reviews that actually ran)
-    from . import costs
-
     if domain_verdict != "skipped":
-        costs.record_usage(
+        pr_cost += costs.record_usage(
             conn, config.EVAL_DOMAIN_MODEL, "eval_domain",
             input_tokens=domain_usage.get("prompt_tokens", 0),
             output_tokens=domain_usage.get("completion_tokens", 0),
@@ -845,15 +864,23 @@ async def evaluate_pr(conn, pr_number: int, tier: str = None) -> dict:
         )
     if leo_verdict not in ("skipped",):
         if tier == "DEEP":
-            costs.record_usage(conn, config.EVAL_LEO_MODEL, "eval_leo", backend="max")
+            pr_cost += costs.record_usage(
+                conn, config.EVAL_LEO_MODEL, "eval_leo",
+                input_tokens=leo_usage.get("prompt_tokens", 0),
+                output_tokens=leo_usage.get("completion_tokens", 0),
+                backend="max",
+            )
         else:
-            costs.record_usage(
+            pr_cost += costs.record_usage(
                 conn, config.EVAL_LEO_STANDARD_MODEL, "eval_leo",
                 input_tokens=leo_usage.get("prompt_tokens", 0),
                 output_tokens=leo_usage.get("completion_tokens", 0),
                 backend="openrouter",
             )
 
+    if pr_cost > 0:
+        conn.execute("UPDATE prs SET cost_usd = cost_usd + ? WHERE number = ?", (pr_cost, pr_number))
+
     return {
         "pr": pr_number,
         "tier": tier,