Add per-review + per-comment token accounting, surfaced only when a PR carries
the new AI-USAGE label (on top of the existing AI-REVIEW trigger).

opencode_review:
- run_opencode now uses `--format json`; parse_opencode_events reconstructs the
  assistant text from `text` events and sums tokens/cost/steps from every
  `step_finish` event (tolerant of noise / missing fields).
- run() measures duration_s around the opencode call and returns (text, usage).
- changed_files(diff) extracts the `+++ b/` paths; the brief now lists them
  under a "Changed files" focus block so the agent grounds findings in the
  diff's neighbourhood instead of unbounded whole-repo walks.

ai_review:
- format_usage_section renders a `## AI usage` block: measured totals
  (in/out/reasoning/cache/cost/steps/duration), the whole-repo scope note, and
  an attributed per-finding table. Per-comment counts are output tokens split by
  each finding's body weight — labelled "attributed" since one model pass
  produces all findings.
- inline_comment_body appends `🪙 ~N tok (X% · attributed output)` when
  attribution is present.
- review_pr gains report_usage; compute_attribution stashes _tok_attrib/_tok_pct.
- format_review_body inserts the usage section between summary and findings.

webhook_server:
- Fire on every pull_request action except `closed` (denylist, was an allowlist)
  — the AI-REVIEW gate + sha dedupe keep this safe.
- AI-USAGE label detection + PRAGENT_USAGE_ALWAYS env drive report_usage.

.opencode factory + review-methodology skill: new "Ground findings in context"
step — read callers/imports/sibling functions per changed file (1-3 files per
finding), no unbounded walks.

Tests: parse_opencode_events (text+usage sum, malformed tolerance, none-usage),
changed_files, compute_attribution math, inline 🪙 line, format_usage_section
totals/table/cost, format_review_body ordering. 68 passing.

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

@@ -161,0 +210,4 @@
+    dur_s = f"{dur}s" if dur is not None else "?"
+    cost = usage.get("cost") or 0.0
+    cost_s = f"${cost:.4f}" if cost else "$0.00"
+    cost_note = (

@@ -236,0 +321,4 @@
+            if isinstance(tok, dict):
+                saw_step = True
+                usage["steps"] += 1
+                usage["input"] += int(tok.get("input") or 0)

@@ -46,0 +45,4 @@
+# the label gate (payload `labels` reflect current state). Gitea emits
+# GitHub-style `action` names (`labeled`, `synchronize`) even though the
+# `X-Gitea-Event-Type` header uses `label_updated` / `synchronized`.
+SKIP_ACTIONS = {"closed"}

@@ -161,0 +190,4 @@
+            f["_tok_pct"] = 1.0 / len(findings)
+        return
+    for f, w in zip(findings, weights):
+        f["_tok_attrib"] = int(round(output_tokens * w / total_w))

@@ -88,3 +98,3 @@
     repo = repo_obj.get("full_name") or ""
 
-    if action not in REVIEW_ACTIONS:
+    if action in SKIP_ACTIONS:

@@ -145,1 +147,4 @@
 
+# Matches unified-diff new-file path headers: `+++ b/path` (and `+++ /dev/null`
+# for deletions, which we skip). Captures the path after the `b/` prefix.
+_NEW_FILE_HEADER_RE = re.compile(r"^\+\+\+ b/(.+?)\s*$")

@@ -236,0 +328,4 @@
+                if isinstance(cache, dict):
+                    usage["cache_read"] += int(cache.get("read") or 0)
+                    usage["cache_write"] += int(cache.get("write") or 0)
+                usage["total"] += int(tok.get("total") or 0)