Merge pull request 'feat: add Canonical Thread Handoff protocol (Closes #505)' (#509) from feat/issue-505-canonical-thread-handoff into master

This commit was merged in pull request #509.
This commit is contained in:
2026-07-09 07:49:13 -05:00
10 changed files with 572 additions and 0 deletions
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"""Canonical Thread Handoff (CTH) protocol for issue and PR comments (#505).
A CTH comment is the authoritative workflow handoff in a Gitea issue or PR
thread. It records current state, decisions, blockers, proof, and the exact
next prompt/action for the next LLM or person.
"""
from __future__ import annotations
import re
from datetime import datetime, timezone
from typing import Any
MARKER = "<!-- cth:v1 -->"
CTH_TERM = "Canonical Thread Handoff"
CTH_ABBREV = "CTH"
CTH_TYPES = frozenset({
"State Handoff",
"Controller Decision",
"Author Handoff",
"Reviewer Handoff",
"Merger Handoff",
"Supersession Notice",
"Blocker",
})
_REQUIRED_BASE_FIELDS = (
"status",
"next owner",
"current blocker",
"decision",
"proof",
"next action",
"ready-to-paste prompt",
)
_HEADING_RE = re.compile(
r"^##\s+CTH:\s*(.+?)\s*$",
re.IGNORECASE | re.MULTILINE,
)
_FIELD_RE = re.compile(
r"^([A-Za-z][A-Za-z0-9 /-]*):\s*(.+?)\s*$",
re.MULTILINE,
)
def format_cth_body(
*,
cth_type: str,
status: str,
next_owner: str,
current_blocker: str = "none",
decision: str = "none",
proof: str = "none",
next_action: str = "none",
ready_to_paste_prompt: str = "none",
extra_fields: dict[str, str] | None = None,
) -> str:
"""Render a canonical CTH comment body."""
normalized_type = (cth_type or "").strip()
if normalized_type not in CTH_TYPES:
raise ValueError(
f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
)
lines = [
MARKER,
f"## CTH: {normalized_type}",
"",
f"Status: {(status or 'unknown').strip() or 'unknown'}",
f"Next owner: {(next_owner or 'unknown').strip() or 'unknown'}",
f"Current blocker: {(current_blocker or 'none').strip() or 'none'}",
f"Decision: {(decision or 'none').strip() or 'none'}",
f"Proof: {(proof or 'none').strip() or 'none'}",
f"Next action: {(next_action or 'none').strip() or 'none'}",
f"Ready-to-paste prompt: {(ready_to_paste_prompt or 'none').strip() or 'none'}",
]
for key, value in (extra_fields or {}).items():
label = (key or "").strip()
if not label:
continue
lines.append(f"{label}: {(value or 'none').strip() or 'none'}")
return "\n".join(lines)
def parse_cth_comment(body: str) -> dict[str, Any] | None:
"""Parse one CTH comment body, or None when not a CTH comment."""
text = body or ""
if MARKER not in text and not _HEADING_RE.search(text):
return None
heading = _HEADING_RE.search(text)
if not heading:
return None
cth_type = heading.group(1).strip()
fields: dict[str, str] = {}
for match in _FIELD_RE.finditer(text):
key = match.group(1).strip().lower()
if key.startswith("cth"):
continue
fields[key] = match.group(2).strip()
return {
"cth_type": cth_type,
"fields": fields,
"raw_body": text,
}
def assess_cth_comment(body: str) -> dict[str, Any]:
"""Validate a CTH comment has required base fields and a known type."""
parsed = parse_cth_comment(body)
reasons: list[str] = []
if not parsed:
return {
"valid": False,
"block": True,
"reasons": ["comment is not a Canonical Thread Handoff (CTH)"],
"parsed": None,
}
cth_type = parsed.get("cth_type") or ""
if cth_type not in CTH_TYPES:
reasons.append(
f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
)
fields = parsed.get("fields") or {}
missing = [name for name in _REQUIRED_BASE_FIELDS if not (fields.get(name) or "").strip()]
if missing:
reasons.append(
"CTH missing required fields: " + ", ".join(missing)
)
vague_prompt = (fields.get("ready-to-paste prompt") or "").strip().lower()
if vague_prompt in {"", "none", "tbd", "n/a", "todo"}:
reasons.append("ready-to-paste prompt must be concrete and paste-ready")
return {
"valid": not reasons,
"block": bool(reasons),
"reasons": reasons,
"parsed": parsed,
"cth_type": cth_type,
}
def find_latest_cth(comments: list[dict[str, Any]]) -> dict[str, Any] | None:
"""Return the newest valid CTH comment from a Gitea comment list."""
latest: dict[str, Any] | None = None
latest_ts: datetime | None = None
for comment in comments or []:
body = comment.get("body") or ""
parsed = parse_cth_comment(body)
if not parsed:
continue
created = _parse_timestamp(comment.get("created_at"))
if latest is None or (created and (latest_ts is None or created >= latest_ts)):
latest = {
"comment_id": comment.get("id"),
"created_at": comment.get("created_at"),
"author": (comment.get("user") or {}).get("login"),
**parsed,
}
latest_ts = created
return latest
def assess_cth_supersedes_non_cth(
*,
latest_cth: dict[str, Any] | None,
narrative_claim: str,
) -> dict[str, Any]:
"""Fail closed when narrative relies on stale non-CTH state despite newer CTH."""
if not latest_cth:
return {"block": False, "reasons": []}
text = (narrative_claim or "").strip()
if not text:
return {"block": False, "reasons": []}
if parse_cth_comment(text):
return {"block": False, "reasons": []}
return {
"block": True,
"reasons": [
"workflow narrative must treat the latest CTH comment as authoritative; "
f"found newer CTH type '{latest_cth.get('cth_type')}' "
f"(comment #{latest_cth.get('comment_id')})"
],
}
def _parse_timestamp(value: str | None) -> datetime | None:
if not value:
return None
text = value.strip()
if text.endswith("Z"):
text = text[:-1] + "+00:00"
try:
parsed = datetime.fromisoformat(text)
except ValueError:
return None
if parsed.tzinfo is None:
return parsed.replace(tzinfo=timezone.utc)
return parsed.astimezone(timezone.utc)
EXAMPLE_SCENARIOS = (
"pr_approved_ready_for_merger",
"pr_request_changes_to_author",
"duplicate_superseded_pr_closure",
"blocked_dirty_root_worktree",
"stale_head_requires_fresh_review",
"issue_implementation_handoff",
)
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# Canonical Thread Handoff (CTH)
**CTH** = **Canonical Thread Handoff**
A CTH comment is the authoritative workflow handoff in a Gitea issue or PR
thread. It records current state, decisions, blockers, proof, and the exact
next prompt/action for the next LLM or person.
CTH comments complement — but do not replace — formal Gitea review state.
A CTH may summarize an APPROVE or REQUEST_CHANGES decision, yet merge gates
still require the live Gitea review verdict.
## CTH comment types
- `CTH: State Handoff`
- `CTH: Controller Decision`
- `CTH: Author Handoff`
- `CTH: Reviewer Handoff`
- `CTH: Merger Handoff`
- `CTH: Supersession Notice`
- `CTH: Blocker`
## Required base template
```md
## CTH: <Type>
Status:
Next owner:
Current blocker:
Decision:
Proof:
Next action:
Ready-to-paste prompt:
```
Extended fields may map to canonical issue/PR state templates from #495 when
that layer is available. Until then, keep the base fields complete.
## Discovery and posting rules
Before acting in an issue or PR thread:
1. **Find the latest CTH comment** before doing work.
2. Treat the **latest valid CTH** as the current handoff state.
3. **Post a new CTH** when you finish, block, skip, supersede, request
changes, approve, or hand off.
4. Do **not** rely on stale non-CTH comments when a newer CTH exists.
5. Casual discussion comments do not need to be CTH comments.
## Examples
### PR approved and ready for merger
```md
## CTH: Reviewer Handoff
Status: approved_at_current_head
Next owner: merger
Current blocker: none
Decision: APPROVE recorded at head abc123...
Proof: gitea_submit_pr_review performed; visible verdict APPROVE
Next action: eligible merger merges PR #N with pinned expected_head_sha
Ready-to-paste prompt: Merge PR #N for issue #M if live head still abc123... and merge gates pass.
```
### PR request-changes back to author
```md
## CTH: Reviewer Handoff
Status: request_changes_at_current_head
Next owner: author
Current blocker: unresolved findings in validation report
Decision: REQUEST_CHANGES at head def456...
Proof: gitea_submit_pr_review performed; blocking review visible
Next action: author fixes findings and pushes; reviewer re-validates fresh head
Ready-to-paste prompt: Fix PR #N review findings, push to feat/issue-M-..., post Author Handoff CTH.
```
### Duplicate / superseded PR closure
```md
## CTH: Supersession Notice
Status: superseded
Next owner: controller
Current blocker: duplicate branch/PR work
Decision: close PR #N; continue on PR #M
Proof: duplicate gate linked open PR #M for issue #K
Next action: controller closes superseded PR and records canonical state
Ready-to-paste prompt: Close superseded PR #N; confirm PR #M remains canonical for issue #K.
```
### Blocked workflow due to dirty root/worktree
```md
## CTH: Blocker
Status: blocked_preflight
Next owner: operator
Current blocker: dirty control checkout / branches worktree mismatch
Decision: stop before mutation
Proof: verify_preflight_purity failed; workspace diagnostics attached
Next action: repair worktree or relaunch MCP from branches/ worktree
Ready-to-paste prompt: Repair dirty workspace, relaunch MCP from branches/review-prN, retry review.
```
### Stale head requiring fresh review
```md
## CTH: Reviewer Handoff
Status: stale_head
Next owner: reviewer
Current blocker: live head differs from pinned review head
Decision: prior approval not valid for current head
Proof: expected_head_sha mismatch at merge gate
Next action: re-run validation and post fresh review decision
Ready-to-paste prompt: Re-validate PR #N at live head, dry-run review gates, submit fresh verdict.
```
### Issue implementation handoff
```md
## CTH: Author Handoff
Status: implementation_complete_pending_review
Next owner: reviewer
Current blocker: none
Decision: PR #N ready for review at head fedcba...
Proof: tests passed in branches/issue-M-...; PR opened with Closes #M
Next action: reviewer acquires lease and validates PR #N
Ready-to-paste prompt: Review PR #N for issue #M; pin head fedcba... before mutations.
```
## Related
- [`llm-workflow-runbooks.md`](llm-workflow-runbooks.md)
- [`../skills/llm-project-workflow/templates/canonical-thread-handoff.md`](../skills/llm-project-workflow/templates/canonical-thread-handoff.md)
- #495 — canonical next-action comment fields
- #496 — fail-closed validation for workflow-changing comments
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@@ -834,6 +834,27 @@ Never imply full-suite success unless the full-suite command itself passed
(`full_suite_passed: true`). A report that hides a failed or skipped check
is worse than a failing report.
## Canonical Thread Handoff (CTH)
**CTH** = **Canonical Thread Handoff** — the authoritative workflow handoff
comment in a Gitea issue or PR thread. See
[`canonical-thread-handoff.md`](canonical-thread-handoff.md) for types,
templates, and examples.
Before acting in an issue or PR thread:
1. **Find the latest CTH comment** before doing work.
2. Treat the **latest valid CTH** as the current handoff state.
3. **Post a new CTH** when you finish, block, skip, supersede, request
changes, approve, or hand off.
4. Do **not** rely on stale non-CTH comments when a newer CTH exists.
A CTH summarizes workflow state for the next session. Formal Gitea review
verdicts remain authoritative for merge gates — a CTH is not merge approval
by itself.
Template: [`../skills/llm-project-workflow/templates/canonical-thread-handoff.md`](../skills/llm-project-workflow/templates/canonical-thread-handoff.md)
## Controller Handoff (required, every task)
Every task — implementation, review, merge, triage, documentation,
@@ -0,0 +1,36 @@
# Template: Canonical Thread Handoff (CTH)
Copy, fill the fields, and post as an issue or PR comment.
```text
## CTH: <Type>
Status: <current workflow state>
Next owner: <author|reviewer|merger|controller|operator>
Current blocker: <none or exact blocker>
Decision: <what was decided this session>
Proof: <commands, SHAs, gate outputs, or explicit pending proof>
Next action: <one concrete step for the next actor>
Ready-to-paste prompt: <full prompt the next session should paste>
```
Allowed `<Type>` values:
- State Handoff
- Controller Decision
- Author Handoff
- Reviewer Handoff
- Merger Handoff
- Supersession Notice
- Blocker
Rules:
- Find the latest CTH comment in the thread before starting work.
- Treat the latest valid CTH as the current source of truth.
- Post a new CTH when you finish, block, skip, supersede, approve, request
changes, or hand off.
- A CTH summarizes workflow state; formal Gitea review verdicts remain
authoritative for merge gates.
Full protocol: `docs/canonical-thread-handoff.md`
@@ -10,6 +10,9 @@ Load the canonical workflow first:
Final report schema: `schemas/review-merge-final-report.md`.
Rules (llm-project-workflow):
- Find the latest CTH comment on the PR/issue thread before starting work.
Post a new CTH: Merger Handoff (or CTH: Blocker) at session end.
Template: skills/llm-project-workflow/templates/canonical-thread-handoff.md
- Repository targeting (#530): pass explicit `remote=`, `org=`, and `repo=` on
every gitea-tools call (e.g. `remote=prgs org=Scaled-Tech-Consulting
repo=Gitea-Tools`). A bare `remote=prgs` can resolve to the wrong default repo
@@ -36,6 +36,9 @@ Load the canonical workflow first:
Final report schema: `schemas/review-merge-final-report.md`.
Rules (llm-project-workflow):
- Find the latest CTH comment on the PR/issue thread before starting work.
Post a new CTH: Reviewer Handoff (or CTH: Blocker) at session end.
Template: skills/llm-project-workflow/templates/canonical-thread-handoff.md
- Repository targeting (#530): pass explicit `remote=`, `org=`, and `repo=` on
every gitea-tools call (e.g. `remote=prgs org=Scaled-Tech-Consulting
repo=Gitea-Tools`). A bare `remote=prgs` can resolve to the wrong default repo
@@ -10,6 +10,9 @@ Final report schema: skills/llm-project-workflow/schemas/work-issue-final-report
Router: skills/llm-project-workflow/SKILL.md (task mode: work-issue)
Rules (llm-project-workflow):
- Find the latest CTH comment on the issue/PR thread before starting work.
Post a new CTH: Author Handoff (or CTH: Blocker) at session end.
Template: skills/llm-project-workflow/templates/canonical-thread-handoff.md
- No repo changes without a tracking issue. If none exists, create one first;
if it can't be created, stop.
- Work only in an isolated branch worktree under branches/. The main checkout
@@ -26,6 +26,12 @@ workflow rules exactly.
## 0. Load the canonical workflow first
Before starting PR work, **find the latest CTH comment** on the PR or linked
issue thread. Treat that CTH as the current handoff state. Post a new
**CTH: Reviewer Handoff**, **CTH: Merger Handoff**, **CTH: Blocker**, or
**CTH: Supersession Notice** when you finish, block, skip, supersede,
approve, request changes, or hand off. See `docs/canonical-thread-handoff.md`.
Before starting PR work, check whether the project provides a canonical PR review/merge workflow through a project skill, runbook, or MCP helper.
If available, load it first and report:
@@ -26,6 +26,12 @@ This is an author/coder workflow. It is not a reviewer workflow.
## 0. Load the canonical workflow first
Before starting issue work, **find the latest CTH comment** on the target
issue or linked PR thread. Treat that CTH as the current handoff state unless
a newer authoritative gate supersedes it. Post a new **CTH: Author Handoff**
(or `CTH: Blocker`) when you finish, block, or hand off.
See `docs/canonical-thread-handoff.md`.
Before starting issue work, check whether the project provides a canonical work-on-issue workflow through a project skill, runbook, or MCP helper.
If available, load it first and report:
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"""Tests for Canonical Thread Handoff (CTH) protocol (#505)."""
from __future__ import annotations
import sys
import unittest
from pathlib import Path
sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
import canonical_thread_handoff as cth # noqa: E402
REPO_ROOT = Path(__file__).resolve().parent.parent
RUNBOOK = REPO_ROOT / "docs" / "llm-workflow-runbooks.md"
PROTOCOL_DOC = REPO_ROOT / "docs" / "canonical-thread-handoff.md"
TEMPLATE = REPO_ROOT / "skills" / "llm-project-workflow/templates" / "canonical-thread-handoff.md"
REVIEW_WORKFLOW = REPO_ROOT / "skills" / "llm-project-workflow/workflows" / "review-merge-pr.md"
WORK_WORKFLOW = REPO_ROOT / "skills" / "llm-project-workflow/workflows" / "work-issue.md"
REVIEW_TEMPLATE = REPO_ROOT / "skills" / "llm-project-workflow/templates" / "review-pr.md"
START_TEMPLATE = REPO_ROOT / "skills" / "llm-project-workflow/templates" / "start-issue.md"
MERGE_TEMPLATE = REPO_ROOT / "skills" / "llm-project-workflow/templates" / "merge-pr.md"
class TestCthModule(unittest.TestCase):
def test_defines_cth_term_and_types(self):
self.assertEqual(cth.CTH_ABBREV, "CTH")
self.assertIn("State Handoff", cth.CTH_TYPES)
self.assertIn("Reviewer Handoff", cth.CTH_TYPES)
self.assertIn("Blocker", cth.CTH_TYPES)
def test_format_and_parse_round_trip(self):
body = cth.format_cth_body(
cth_type="Author Handoff",
status="implementation_complete",
next_owner="reviewer",
current_blocker="none",
decision="PR opened",
proof="pytest passed",
next_action="review PR #9",
ready_to_paste_prompt="Review PR #9 for issue #5",
)
parsed = cth.parse_cth_comment(body)
self.assertIsNotNone(parsed)
self.assertEqual(parsed["cth_type"], "Author Handoff")
self.assertEqual(parsed["fields"]["status"], "implementation_complete")
self.assertEqual(parsed["fields"]["next owner"], "reviewer")
def test_valid_cth_passes_assessment(self):
body = cth.format_cth_body(
cth_type="Reviewer Handoff",
status="approved",
next_owner="merger",
current_blocker="none",
decision="APPROVE",
proof="review id 42",
next_action="merge if gates pass",
ready_to_paste_prompt="Merge PR #12 with pinned head abcdef0123456789abcdef0123456789abcdef01",
)
result = cth.assess_cth_comment(body)
self.assertFalse(result["block"])
self.assertTrue(result["valid"])
def test_missing_fields_fail_closed(self):
body = "## CTH: Blocker\n\nStatus: blocked\n"
result = cth.assess_cth_comment(body)
self.assertTrue(result["block"])
self.assertIn("missing required fields", result["reasons"][0])
def test_find_latest_cth_prefers_newer_comment(self):
older = cth.format_cth_body(
cth_type="State Handoff",
status="old",
next_owner="author",
current_blocker="none",
decision="old",
proof="old",
next_action="old",
ready_to_paste_prompt="old prompt text here",
)
newer = cth.format_cth_body(
cth_type="Reviewer Handoff",
status="new",
next_owner="merger",
current_blocker="none",
decision="approve",
proof="new",
next_action="merge",
ready_to_paste_prompt="merge PR #3 now with pinned head",
)
comments = [
{"id": 1, "created_at": "2026-07-01T10:00:00Z", "body": older},
{"id": 2, "created_at": "2026-07-02T10:00:00Z", "body": newer},
]
latest = cth.find_latest_cth(comments)
self.assertEqual(latest["comment_id"], 2)
self.assertEqual(latest["cth_type"], "Reviewer Handoff")
def test_cth_does_not_replace_formal_reviews_documented_in_protocol(self):
text = PROTOCOL_DOC.read_text(encoding="utf-8")
self.assertIn("do not replace", text.lower())
self.assertIn("formal Gitea review", text)
def test_examples_cover_required_scenarios(self):
text = PROTOCOL_DOC.read_text(encoding="utf-8")
expected_phrases = (
"PR approved and ready for merger",
"request-changes back to author",
"superseded PR closure",
"dirty root/worktree",
"Stale head requiring fresh review",
"Issue implementation handoff",
)
for phrase in expected_phrases:
self.assertIn(phrase, text)
class TestCthDocumentationChecks(unittest.TestCase):
def test_runbook_references_cth_discovery_and_posting(self):
text = RUNBOOK.read_text(encoding="utf-8")
self.assertIn("Canonical Thread Handoff", text)
self.assertIn("Find the latest CTH comment", text)
self.assertIn("Post a new CTH", text)
self.assertIn("canonical-thread-handoff.md", text)
def test_workflows_reference_cth_rules(self):
for path in (REVIEW_WORKFLOW, WORK_WORKFLOW):
text = path.read_text(encoding="utf-8")
self.assertIn("latest CTH comment", text)
self.assertIn("canonical-thread-handoff.md", text)
def test_prompt_templates_reference_cth_rules(self):
for path in (REVIEW_TEMPLATE, START_TEMPLATE, MERGE_TEMPLATE, TEMPLATE):
text = path.read_text(encoding="utf-8")
self.assertIn("CTH", text)
self.assertIn("canonical-thread-handoff", text)
if __name__ == "__main__":
unittest.main()