fix: auto-detect issue number in cycle retro from git branch name

cycle_retro.py now extracts the issue number from the current git branch
(e.g. kimi/issue-492 → 492) when --issue is not explicitly provided.

backfill_retro.py now skips the PR number suffix that Gitea appends to
titles (e.g. (#491)) so it doesn't confuse PR numbers with issue numbers.

Fixes #492

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

scripts/backfill_retro.py

@@ -94,12 +94,17 @@ def extract_cycle_number(title: str) -> int | None:
     return int(m.group(1)) if m else None
 
 
-def extract_issue_number(title: str, body: str) -> int | None:
+def extract_issue_number(title: str, body: str, pr_number: int | None = None) -> int | None:
-    # Try body first (usually has "closes #N")
+    """Extract the issue number from PR body/title, ignoring the PR number itself.
+
+    Gitea appends "(#N)" to PR titles where N is the PR number — skip that
+    so we don't confuse it with the linked issue.
+    """
     for text in [body or "", title]:
-        m = ISSUE_RE.search(text)
+        for m in ISSUE_RE.finditer(text):
-        if m:
+            num = int(m.group(1))
-            return int(m.group(1))
+            if num != pr_number:
+                return num
     return None
 
 
@@ -140,7 +145,7 @@ def main():
         else:
             cycle_counter = max(cycle_counter, cycle)
 
-        issue = extract_issue_number(title, body)
+        issue = extract_issue_number(title, body, pr_number=pr_num)
         issue_type = classify_pr(title, body)
         duration = estimate_duration(pr)
         diff = get_pr_diff_stats(token, pr_num)

scripts/cycle_retro.py

@@ -44,6 +44,8 @@ from __future__ import annotations
 
 import argparse
 import json
+import re
+import subprocess
 import sys
 from datetime import datetime, timezone
 from pathlib import Path
@@ -56,6 +58,23 @@ EPOCH_COUNTER_FILE = REPO_ROOT / ".loop" / "retro" / ".epoch_counter"
 # How many recent entries to include in rolling summary
 SUMMARY_WINDOW = 50
 
+# Branch patterns that encode an issue number, e.g. kimi/issue-492
+BRANCH_ISSUE_RE = re.compile(r"issue[/-](\d+)", re.IGNORECASE)
+
+
+def detect_issue_from_branch() -> int | None:
+    """Try to extract an issue number from the current git branch name."""
+    try:
+        branch = subprocess.check_output(
+            ["git", "rev-parse", "--abbrev-ref", "HEAD"],
+            stderr=subprocess.DEVNULL,
+            text=True,
+        ).strip()
+    except (subprocess.CalledProcessError, FileNotFoundError):
+        return None
+    m = BRANCH_ISSUE_RE.search(branch)
+    return int(m.group(1)) if m else None
+
 
 # ── Epoch turnover ────────────────────────────────────────────────────────
 
@@ -230,6 +249,10 @@ def update_summary() -> None:
 def main() -> None:
     args = parse_args()
 
+    # Auto-detect issue from branch when not explicitly provided
+    if args.issue is None:
+        args.issue = detect_issue_from_branch()
+
     # Reject idle cycles — no issue and no duration means nothing happened
     if not args.issue and args.duration == 0:
         print(f"[retro] Cycle {args.cycle} skipped — idle (no issue, no duration)")

tests/loop/test_cycle_retro.py

@@ -0,0 +1,86 @@
+"""Tests for scripts/cycle_retro.py issue auto-detection."""
+
+from __future__ import annotations
+
+# Import the module under test — it's a script so we import the helpers directly
+import importlib
+import subprocess
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+SCRIPTS_DIR = Path(__file__).resolve().parent.parent.parent / "scripts"
+
+
+@pytest.fixture(autouse=True)
+def _add_scripts_to_path(monkeypatch):
+    monkeypatch.syspath_prepend(str(SCRIPTS_DIR))
+
+
+@pytest.fixture()
+def mod():
+    """Import cycle_retro as a module."""
+    return importlib.import_module("cycle_retro")
+
+
+class TestDetectIssueFromBranch:
+    def test_kimi_issue_branch(self, mod):
+        with patch.object(subprocess, "check_output", return_value="kimi/issue-492\n"):
+            assert mod.detect_issue_from_branch() == 492
+
+    def test_plain_issue_branch(self, mod):
+        with patch.object(subprocess, "check_output", return_value="issue-123\n"):
+            assert mod.detect_issue_from_branch() == 123
+
+    def test_issue_slash_number(self, mod):
+        with patch.object(subprocess, "check_output", return_value="fix/issue/55\n"):
+            assert mod.detect_issue_from_branch() == 55
+
+    def test_no_issue_in_branch(self, mod):
+        with patch.object(subprocess, "check_output", return_value="main\n"):
+            assert mod.detect_issue_from_branch() is None
+
+    def test_feature_branch(self, mod):
+        with patch.object(subprocess, "check_output", return_value="feature/add-widget\n"):
+            assert mod.detect_issue_from_branch() is None
+
+    def test_git_not_available(self, mod):
+        with patch.object(subprocess, "check_output", side_effect=FileNotFoundError):
+            assert mod.detect_issue_from_branch() is None
+
+    def test_git_fails(self, mod):
+        with patch.object(
+            subprocess,
+            "check_output",
+            side_effect=subprocess.CalledProcessError(1, "git"),
+        ):
+            assert mod.detect_issue_from_branch() is None
+
+
+class TestBackfillExtractIssueNumber:
+    """Tests for backfill_retro.extract_issue_number PR-number filtering."""
+
+    @pytest.fixture()
+    def backfill(self):
+        return importlib.import_module("backfill_retro")
+
+    def test_body_has_issue(self, backfill):
+        assert backfill.extract_issue_number("fix: foo (#491)", "Fixes #490", pr_number=491) == 490
+
+    def test_title_skips_pr_number(self, backfill):
+        assert backfill.extract_issue_number("fix: foo (#491)", "", pr_number=491) is None
+
+    def test_title_with_issue_and_pr(self, backfill):
+        # [loop-cycle-538] refactor: ... (#459) (#481)
+        assert (
+            backfill.extract_issue_number(
+                "[loop-cycle-538] refactor: remove dead airllm (#459) (#481)",
+                "",
+                pr_number=481,
+            )
+            == 459
+        )
+
+    def test_no_pr_number_provided(self, backfill):
+        assert backfill.extract_issue_number("fix: foo (#491)", "") == 491