Files
Gitea-Tools/pr_sync_status.py
T
sysadminandClaude Opus 4.8 eac7afe5cb fix(mcp): derive checks requirement from live branch protection (Closes #751)
`gitea_assess_pr_sync_status` could permanently block a merge-ready PR whose
head commit had no status contexts.

Gitea's combined commit-status endpoint reports `state: pending` both when a
check is executing and when the status-context collection is empty. The
wrapper took that `state` verbatim, and `checks_required` defaulted to True
with no production path ever setting it, so "no CI configured" was
indistinguishable from "CI is running" and waiting could never resolve it.

Root cause spans the whole dataflow, not one call site:

* the wrapper read only the combined `state` and never counted contexts;
  its `checks_status="none"` fallback was unreachable for any truthy state
* `pr_sync_status.assess_pr_sync_status` defaulted `checks_required=True`
* the MCP wrapper exposed no derived `checks_required` and never passed one
* the branch-protection reader fetched the payload carrying
  `enable_status_check` / `status_check_contexts` and discarded both

Changes:

* `pr_sync_status.py`: add `classify_commit_checks` plus explicit
  CHECKS_* classifications (success / failure / pending / none /
  not_required / missing_required / unknown). The combined state is
  recorded for observability but is never evidence that CI is executing.
  Aggregation is fail-closed and newest-wins per context.
* `pr_sync_status.py`: rewrite the merge_now checks gate to consume the
  derived `checks_required`, distinguish the new classifications with
  precise blocker reasons, and fail closed on unrecognized vocabulary.
  The previous gate let any value outside its fixed vocabulary fall
  through to merge_now.
* `gitea_mcp_server.py`: add `_branch_protection_policy` deriving both the
  current-base rule and the status-check requirement from one live read;
  `_branch_protection_requires_current_base` is retained as a thin
  accessor with unchanged semantics. Add `_commit_checks_snapshot` which
  returns the context collection alongside the combined state.
* `gitea_mcp_server.py`: wire the derived `checks_required` into the
  production assessment path and report `checks_evidence`.

`checks_required` is always derived from live evidence and is deliberately
not a caller-supplied input, so no session can declare checks optional
without proof. Live classification also outranks a caller-supplied
`checks_status`, which can no longer mask a real required-check failure.
An unreadable protection policy or status collection stays fail-closed.

Approval, current-head, current-base, mergeability, conflict, role, lease
and merge-authorization gates are unchanged.

Tests: `tests/test_issue_751_checks_assessor.py` (40 tests).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
2026-07-18 17:38:54 -04:00

850 lines
33 KiB
Python

"""PR synchronization and conflict-remediation lifecycle (#PR-SYNC).
Pure assessment helpers for:
* ``gitea_assess_pr_sync_status`` — recommend the next sanctioned action for an
open PR when the base branch advances, approvals go stale, or conflicts appear.
* ``gitea_update_pr_branch_by_merge`` preflight — author-only, fail-closed pin
of both PR head and live base head; never rebase/force-push.
All recommendation logic is hermetic (no network) so unit tests cover every
acceptance path without Gitea credentials.
"""
from __future__ import annotations
import re
from typing import Any
_FULL_SHA = re.compile(r"^[0-9a-f]{40}$", re.IGNORECASE)
# Recommended next actions (controller / skill vocabulary).
ACTION_MERGE_NOW = "merge_now"
ACTION_UPDATE_BRANCH_BY_MERGE = "update_branch_by_merge"
ACTION_AUTHOR_CONFLICT_REMEDIATION = "author_conflict_remediation"
ACTION_FRESH_REVIEW_REQUIRED = "fresh_review_required"
ACTION_BLOCKED = "blocked"
_VALID_ACTIONS = frozenset({
ACTION_MERGE_NOW,
ACTION_UPDATE_BRANCH_BY_MERGE,
ACTION_AUTHOR_CONFLICT_REMEDIATION,
ACTION_FRESH_REVIEW_REQUIRED,
ACTION_BLOCKED,
})
# Author-only mutation; reviewer/merger must never update author branches.
_AUTHOR_UPDATE_ROLES = frozenset({"author"})
_DENIED_UPDATE_ROLES = frozenset({"reviewer", "merger", "reconciler", "mixed", "limited"})
# Allowed Gitea update style — merge only (never rebase).
UPDATE_STYLE_MERGE = "merge"
_FORBIDDEN_UPDATE_STYLES = frozenset({"rebase", "rebase-merge", "squash", "force"})
# ── Commit check classifications (#751) ──────────────────────────────────
# Gitea's *combined* commit status reports ``state: pending`` both when a real
# check is executing and when the status-context collection is empty. Reading
# ``state`` alone therefore cannot distinguish "CI is running" from "no CI
# exists", which permanently blocks a merge-ready PR that no check will ever
# report on. These classifications are derived from the actual context
# collection plus the live branch-protection policy.
CHECKS_SUCCESS = "success"
CHECKS_FAILURE = "failure"
CHECKS_PENDING = "pending"
CHECKS_NONE = "none" # configured/produced nothing
CHECKS_NOT_REQUIRED = "not_required" # protection does not require checks
CHECKS_MISSING_REQUIRED = "missing_required" # required contexts have no result
CHECKS_UNKNOWN = "unknown" # indeterminable — fail closed
# Values that permit merge_now when checks are required.
_CHECKS_OK = frozenset({"success", "passed", "ok", "skipped", "not_required"})
# Raw per-context state vocabularies reported by Gitea.
_CTX_SUCCESS = frozenset({"success", "passed", "ok"})
_CTX_FAILURE = frozenset({"failure", "failed", "error", "cancelled", "canceled"})
_CTX_PENDING = frozenset({"pending", "running", "queued", "expected"})
_CTX_SKIPPED = frozenset({"skipped", "neutral"})
def _normalize_context_rows(statuses: Any) -> list[dict[str, str]]:
"""Reduce a raw status collection to newest-wins ``{context, state}`` rows.
Gitea returns the status collection newest-first, so the first row seen for
a context wins. Rows without a usable state are discarded rather than being
silently treated as passing.
"""
rows: list[dict[str, str]] = []
seen: set[str] = set()
if not isinstance(statuses, list):
return rows
for raw in statuses:
if not isinstance(raw, dict):
continue
context = (raw.get("context") or raw.get("name") or "").strip()
state = (raw.get("status") or raw.get("state") or "").strip().lower()
if not state:
continue
key = context or f"__unnamed__{len(rows)}"
if key in seen:
continue
seen.add(key)
rows.append({"context": context, "state": state})
return rows
def _aggregate_context_states(rows: list[dict[str, str]]) -> str:
"""Fail-closed aggregate: failure > pending > unknown-state > success."""
states = {row["state"] for row in rows}
if states & _CTX_FAILURE:
return CHECKS_FAILURE
if states & _CTX_PENDING:
return CHECKS_PENDING
unresolved = states - _CTX_SUCCESS - _CTX_SKIPPED
if unresolved:
# An unrecognized context state must never read as success.
return CHECKS_UNKNOWN
return CHECKS_SUCCESS
def classify_commit_checks(
*,
combined_state: str | None = None,
statuses: Any = None,
checks_enabled: bool | None = None,
required_contexts: Any = None,
policy_determinable: bool = True,
status_determinable: bool = True,
) -> dict[str, Any]:
"""Classify head checks from live evidence (#751).
``combined_state`` is deliberately **not** authoritative: it is recorded for
observability but never used to infer that CI is executing. The context
collection and the live protection policy decide.
Returns ``checks_status`` (one of the ``CHECKS_*`` values), the derived
``checks_required`` flag, and structured ``reasons``.
"""
reasons: list[str] = []
rows = _normalize_context_rows(statuses)
required = [
str(ctx).strip()
for ctx in (required_contexts or [])
if str(ctx or "").strip()
]
observed_combined = (combined_state or "").strip().lower() or None
result: dict[str, Any] = {
"checks_status": CHECKS_UNKNOWN,
"checks_required": True,
"combined_state": observed_combined,
"context_count": len(rows),
"observed_contexts": [row["context"] for row in rows],
"required_contexts": required,
"missing_required_contexts": [],
"policy_determinable": bool(policy_determinable),
"status_determinable": bool(status_determinable),
"reasons": reasons,
}
# Policy unreadable → never assume checks are optional.
if not policy_determinable:
reasons.append(
"branch-protection check policy could not be read; cannot prove "
"whether status checks are required (fail closed)"
)
return result
if checks_enabled is False:
result["checks_required"] = False
result["checks_status"] = CHECKS_NOT_REQUIRED
reasons.append(
"live branch protection does not require status checks for the base "
"branch; head status contexts do not gate merge"
)
return result
if checks_enabled is None:
reasons.append(
"branch-protection status-check requirement is indeterminate "
"(fail closed)"
)
return result
# Checks are required from here on.
if not status_determinable:
reasons.append(
"head commit status collection could not be read while branch "
"protection requires status checks (fail closed)"
)
return result
if required:
by_context = {row["context"]: row["state"] for row in rows if row["context"]}
missing = [ctx for ctx in required if ctx not in by_context]
if missing:
result["missing_required_contexts"] = missing
result["checks_status"] = CHECKS_MISSING_REQUIRED
reasons.append(
"branch protection requires status context(s) "
f"{', '.join(missing)} but no matching status result exists at "
"the head commit (fail closed)"
)
return result
matched = [
{"context": ctx, "state": by_context[ctx]} for ctx in required
]
result["checks_status"] = _aggregate_context_states(matched)
reasons.append(
f"evaluated {len(matched)} required status context(s) from live "
"branch protection; unrelated contexts were ignored"
)
return result
# Status checks enabled with no specific required contexts configured.
if not rows:
result["checks_status"] = CHECKS_NONE
reasons.append(
"branch protection enables status checks but no status context was "
"produced for the head commit"
)
if observed_combined in _CTX_PENDING:
reasons.append(
f"combined commit state '{observed_combined}' does not indicate "
"executing CI because the status-context collection is empty"
)
return result
result["checks_status"] = _aggregate_context_states(rows)
reasons.append(
f"aggregated {len(rows)} reported status context(s); branch protection "
"configures no explicit required-context list"
)
return result
def _normalize_sha(value: str | None) -> str | None:
text = (value or "").strip().lower()
if not text:
return None
return text if _FULL_SHA.match(text) else None
def _normalize_role(role: str | None) -> str:
return (role or "").strip().lower() or "unknown"
def assess_pr_sync_status(
*,
host: str | None = None,
org: str | None = None,
repo: str | None = None,
pr_number: int,
pr_state: str | None = None,
source_branch: str | None = None,
pr_head_sha: str | None = None,
base_head_sha: str | None = None,
commits_behind: int | None = None,
mergeable: bool | None = None,
has_conflicts: bool | None = None,
branch_protection_requires_current_base: bool | None = None,
approval_at_current_head: bool | None = None,
checks_status: str | None = None,
active_author_lock: bool | None = None,
active_reviewer_lease: bool | None = None,
active_merger_lease: bool | None = None,
prepared_verdict_head_sha: str | None = None,
checks_required: bool = True,
) -> dict[str, Any]:
"""Recommend the next sanctioned PR lifecycle action.
Decision order (fail closed):
1. Incomplete identity / open state / head SHAs → ``blocked``
2. Conflicts (or mergeable false with conflict signal) →
``author_conflict_remediation``
3. Head changed after approval / prepared verdict for former head →
``fresh_review_required`` (unless conflicts already routed author work)
4. Behind live base + branch protection requires current base +
auto-mergeable → ``update_branch_by_merge``
5. Approval at current head + mergeable + checks ok (+ update not
required) → ``merge_now``
6. Otherwise ``blocked`` with structured reasons
"""
reasons: list[str] = []
pr_head = _normalize_sha(pr_head_sha)
base_head = _normalize_sha(base_head_sha)
prepared_head = _normalize_sha(prepared_verdict_head_sha)
state = (pr_state or "").strip().lower()
checks = (checks_status or "unknown").strip().lower()
behind = commits_behind if isinstance(commits_behind, int) and commits_behind >= 0 else None
requires_current = bool(branch_protection_requires_current_base)
approval_ok = bool(approval_at_current_head)
# Derive conflict when caller only supplies mergeable=False.
if has_conflicts is None and mergeable is False:
has_conflicts = True
conflicts = bool(has_conflicts) if has_conflicts is not None else None
result: dict[str, Any] = {
"host": (host or "").strip() or None,
"org": (org or "").strip() or None,
"repo": (repo or "").strip() or None,
"pr_number": pr_number,
"pr_state": state or None,
"source_branch": (source_branch or "").strip() or None,
"pr_head_sha": pr_head,
"base_head_sha": base_head,
"commits_behind": behind,
"mergeable": mergeable,
"has_conflicts": conflicts,
"branch_protection_requires_current_base": requires_current,
"approval_at_current_head": approval_ok if approval_at_current_head is not None else None,
"checks_status": checks,
"checks_required": bool(checks_required),
"active_locks_and_leases": {
"author_lock": bool(active_author_lock) if active_author_lock is not None else None,
"reviewer_lease": bool(active_reviewer_lease) if active_reviewer_lease is not None else None,
"merger_lease": bool(active_merger_lease) if active_merger_lease is not None else None,
},
"prepared_verdict_head_sha": prepared_head,
"recommended_next_action": ACTION_BLOCKED,
"approval_valid_for_merge": False,
"stale_approval": False,
"stale_prepared_verdict": False,
"reasons": reasons,
"success": True,
"performed": False,
}
if not isinstance(pr_number, int) or pr_number <= 0:
reasons.append("pr_number must be a positive integer (fail closed)")
return result
if state and state not in ("open",):
reasons.append(f"PR is not open (state={state}); cannot synchronize or merge")
result["recommended_next_action"] = ACTION_BLOCKED
return result
if not state:
reasons.append("PR state missing (fail closed)")
return result
if pr_head is None:
reasons.append(
"exact PR head SHA missing or not a full 40-char hex SHA (fail closed)"
)
if base_head is None:
reasons.append(
"exact live base head SHA missing or not a full 40-char hex SHA (fail closed)"
)
if behind is None:
reasons.append("commits_behind missing or invalid (fail closed)")
if mergeable is None:
reasons.append("mergeable signal missing (fail closed)")
if approval_at_current_head is None:
reasons.append("approval_at_current_head missing (fail closed)")
if branch_protection_requires_current_base is None:
reasons.append(
"branch_protection_requires_current_base missing (fail closed)"
)
if reasons:
result["recommended_next_action"] = ACTION_BLOCKED
return result
# Stale prepared verdict / approval across heads.
stale_prepared = bool(prepared_head and prepared_head != pr_head)
result["stale_prepared_verdict"] = stale_prepared
stale_approval = not approval_ok
result["stale_approval"] = stale_approval
result["approval_valid_for_merge"] = bool(approval_ok and not stale_prepared)
# ── Conflicts: author remediation in dedicated worktree ──────────────
if conflicts is True or mergeable is False:
if conflicts is True or mergeable is False:
# Distinguish pure non-mergeable without explicit conflict flag
# still routes author remediation (Gitea cannot auto-update).
reasons.append(
f"PR #{pr_number} has conflicts or is not mergeable at head "
f"{pr_head}; route author conflict remediation in the existing "
"issue/PR worktree under branches/ (never force-push or rebase)"
)
if stale_approval:
reasons.append(
"any approval at a former head is invalid; after remediation "
"require a fresh independent review at the new exact head"
)
result["recommended_next_action"] = ACTION_AUTHOR_CONFLICT_REMEDIATION
result["approval_valid_for_merge"] = False
return result
# ── Stale approval / prepared verdict at former head ─────────────────
if not approval_ok or stale_prepared:
if behind and behind > 0 and requires_current and mergeable is True:
# Must update first; update will also invalidate approval.
reasons.append(
f"PR is {behind} commit(s) behind live base and branch protection "
"requires current base; automatic merge-from-base is available"
)
reasons.append(
"approval is not valid at the current head (or prepared verdict "
"is head-scoped to a former SHA); after update require fresh review"
)
result["recommended_next_action"] = ACTION_UPDATE_BRANCH_BY_MERGE
result["approval_valid_for_merge"] = False
return result
reasons.append(
"approval is not valid at the exact current PR head "
f"({pr_head}); never reuse a former-head approval for merge"
)
if stale_prepared:
reasons.append(
f"prepared verdict pinned to former head {prepared_head} cannot "
f"authorize review/merge at current head {pr_head}"
)
if active_reviewer_lease:
reasons.append(
"active reviewer lease must be released or superseded for the "
"new head before a fresh independent review"
)
if active_merger_lease:
reasons.append(
"active merger lease cannot cross heads; release or re-acquire "
"at the new exact head"
)
result["recommended_next_action"] = ACTION_FRESH_REVIEW_REQUIRED
result["approval_valid_for_merge"] = False
return result
# ── Outdated + protection requires current base, auto-updatable ──────
if behind and behind > 0 and requires_current:
if mergeable is True and conflicts is not True:
reasons.append(
f"PR is {behind} commit(s) behind live base {base_head}; "
"branch protection requires the PR branch to contain current base; "
"Gitea can merge base into the PR branch without conflicts"
)
reasons.append(
"route author-only update_branch_by_merge; never rebase or force-push; "
"new head invalidates prior approval and requires fresh independent review"
)
result["recommended_next_action"] = ACTION_UPDATE_BRANCH_BY_MERGE
# Approval today is at old head that will change — not mergeable yet
# for final merge until re-reviewed, but assess marks update path.
result["approval_valid_for_merge"] = False
result["stale_approval"] = True # will become stale after update
return result
reasons.append(
"update required by branch protection but automatic merge is not available"
)
result["recommended_next_action"] = ACTION_BLOCKED
return result
# ── Checks gate for merge_now (#751) ─────────────────────────────────
# ``checks_required`` is derived from the live branch-protection policy by
# the production caller. When protection does not require status checks,
# head contexts cannot gate the merge and this whole gate is skipped.
if not checks_required:
reasons.append(
"live branch protection does not require status checks; head check "
f"state ({checks}) does not gate merge"
)
elif checks not in _CHECKS_OK:
if checks in _CTX_PENDING:
reasons.append(f"required checks are not finished (status={checks})")
elif checks in _CTX_FAILURE:
reasons.append(f"required checks failed (status={checks})")
elif checks == CHECKS_MISSING_REQUIRED:
reasons.append(
"branch protection configures required status context(s) but no "
"matching status result exists at the current head (fail closed)"
)
elif checks == CHECKS_NONE:
reasons.append(
"branch protection requires status checks but no status context "
"was produced for the current head (fail closed); an empty "
"status collection is not executing CI"
)
elif checks == CHECKS_UNKNOWN:
reasons.append("checks status unknown (fail closed)")
else:
# Unrecognized vocabulary must never fall through to merge_now.
reasons.append(
f"unrecognized checks status '{checks}' cannot prove required "
"checks passed (fail closed)"
)
result["recommended_next_action"] = ACTION_BLOCKED
return result
# ── Ready to merge without update ────────────────────────────────────
# Includes: current with approval; outdated when update is NOT required.
if approval_ok and mergeable is True and conflicts is not True:
if behind and behind > 0 and not requires_current:
reasons.append(
f"PR is {behind} commit(s) behind live base but branch protection "
"does not require the latest base; preserve the approved head"
)
else:
reasons.append(
"PR has a valid approval at the exact current head, is conflict-free "
"and mergeable; do not update the branch unnecessarily"
)
reasons.append("route directly to the sanctioned merger workflow (merge_now)")
result["recommended_next_action"] = ACTION_MERGE_NOW
result["approval_valid_for_merge"] = True
return result
reasons.append("no sanctioned next action matched the observed PR state (fail closed)")
result["recommended_next_action"] = ACTION_BLOCKED
return result
def assess_update_pr_branch_preflight(
*,
role_kind: str | None,
expected_pr_head_sha: str | None,
live_pr_head_sha: str | None,
expected_base_head_sha: str | None,
live_base_head_sha: str | None,
has_conflicts: bool | None = None,
mergeable: bool | None = None,
style: str | None = UPDATE_STYLE_MERGE,
has_author_lock: bool | None = None,
worktree_path: str | None = None,
worktree_owns_source_branch: bool | None = None,
control_checkout_clean: bool | None = None,
master_parity_ok: bool | None = None,
force_push: bool = False,
rebase: bool = False,
) -> dict[str, Any]:
"""Author-only preflight for update-by-merge; fail closed on any race.
When conflicts exist, returns a structured author-remediation handoff and
sets ``mutation_allowed=False`` so no partial remote update is performed.
"""
reasons: list[str] = []
role = _normalize_role(role_kind)
exp_pr = _normalize_sha(expected_pr_head_sha)
live_pr = _normalize_sha(live_pr_head_sha)
exp_base = _normalize_sha(expected_base_head_sha)
live_base = _normalize_sha(live_base_head_sha)
style_norm = (style or "").strip().lower() or UPDATE_STYLE_MERGE
conflicts = has_conflicts
if conflicts is None and mergeable is False:
conflicts = True
result: dict[str, Any] = {
"mutation_allowed": False,
"performed": False,
"style": style_norm,
"role_kind": role,
"expected_pr_head_sha": exp_pr,
"live_pr_head_sha": live_pr,
"expected_base_head_sha": exp_base,
"live_base_head_sha": live_base,
"head_race": False,
"base_race": False,
"has_conflicts": conflicts,
"author_remediation_handoff": False,
"approval_invalidated_for_former_head": False,
"force_push": bool(force_push),
"rebase": bool(rebase),
"reasons": reasons,
"success": True,
}
# Role gate — author only.
if role not in _AUTHOR_UPDATE_ROLES:
reasons.append(
f"role '{role}' cannot update an author PR branch "
"(author-only; reviewer/merger denial)"
)
return result
if force_push:
reasons.append("force-push is forbidden for PR branch update (fail closed)")
return result
if rebase or style_norm in _FORBIDDEN_UPDATE_STYLES:
reasons.append(
f"update style '{style_norm}' forbidden; only style=merge is allowed "
"(never rebase)"
)
return result
if style_norm != UPDATE_STYLE_MERGE:
reasons.append(
f"unknown update style '{style_norm}'; expected '{UPDATE_STYLE_MERGE}'"
)
return result
if not exp_pr or not live_pr:
reasons.append(
"expected and live PR head SHAs must be full 40-char hex (fail closed)"
)
if not exp_base or not live_base:
reasons.append(
"expected and live base head SHAs must be full 40-char hex (fail closed)"
)
if reasons:
return result
if exp_pr != live_pr:
result["head_race"] = True
reasons.append(
f"PR head race: expected {exp_pr} but live is {live_pr} "
"(fail closed; no partial mutation)"
)
return result
if exp_base != live_base:
result["base_race"] = True
reasons.append(
f"base head race: expected {exp_base} but live is {live_base} "
"(fail closed; no partial mutation)"
)
return result
if has_author_lock is not True:
reasons.append(
"existing issue/PR lock required before update_branch_by_merge (fail closed)"
)
wt = (worktree_path or "").strip()
if not wt:
reasons.append("existing PR worktree path required under branches/ (fail closed)")
else:
norm = wt.replace("\\", "/")
if "/branches/" not in norm and not norm.startswith("branches/"):
reasons.append(
f"worktree_path '{wt}' must be under branches/ (fail closed)"
)
if worktree_owns_source_branch is False:
reasons.append(
"worktree does not own the PR source branch (fail closed)"
)
if control_checkout_clean is False:
reasons.append("control checkout is not clean (fail closed)")
if master_parity_ok is False:
reasons.append("runtime/master parity failed (fail closed)")
if conflicts is True:
result["author_remediation_handoff"] = True
reasons.append(
"conflicts present: return structured author-remediation handoff "
"without creating a partial remote update"
)
reasons.append(
"resolve conflicts explicitly in the existing dedicated worktree, "
"run focused and regression tests, commit/push via sanctioned author "
"workflow, then route the new exact head to independent review"
)
return result
if mergeable is False and conflicts is not False:
result["author_remediation_handoff"] = True
reasons.append(
"PR is not mergeable; refuse automatic update and hand off to "
"author conflict remediation (fail closed)"
)
return result
if reasons:
return result
result["mutation_allowed"] = True
reasons.append(
"preflight passed: author may merge live base into the PR branch via "
"native MCP update (style=merge only)"
)
return result
def assess_post_update_head_transition(
*,
former_pr_head_sha: str | None,
new_pr_head_sha: str | None,
former_approval_head_sha: str | None = None,
former_reviewer_lease_head_sha: str | None = None,
former_merger_lease_head_sha: str | None = None,
prepared_verdict_head_sha: str | None = None,
) -> dict[str, Any]:
"""After a successful update-by-merge, invalidate cross-head artifacts.
The new head never inherits approval, reviewer/merger leases, or prepared
verdicts from the former head.
"""
former = _normalize_sha(former_pr_head_sha)
new = _normalize_sha(new_pr_head_sha)
reasons: list[str] = []
result: dict[str, Any] = {
"former_pr_head_sha": former,
"new_pr_head_sha": new,
"head_changed": bool(former and new and former != new),
"approval_invalidated": False,
"reviewer_lease_superseded": False,
"merger_lease_superseded": False,
"prepared_verdict_invalidated": False,
"recommended_next_action": ACTION_BLOCKED,
"reasons": reasons,
"success": True,
}
if not former or not new:
reasons.append("former and new PR head SHAs required (fail closed)")
return result
if former == new:
reasons.append(
"PR head unchanged after update; unexpected for merge-from-base"
)
result["recommended_next_action"] = ACTION_BLOCKED
return result
result["head_changed"] = True
# Approval at former head is always void at new head.
former_approval = _normalize_sha(former_approval_head_sha) or former
if former_approval != new:
result["approval_invalidated"] = True
reasons.append(
f"approval for former head {former_approval} is invalid at new head "
f"{new}; never preserve approval across a head change"
)
rev_lease = _normalize_sha(former_reviewer_lease_head_sha)
if rev_lease and rev_lease != new:
result["reviewer_lease_superseded"] = True
reasons.append(
f"reviewer lease for head {rev_lease} cannot cross to {new}; "
"release or supersede before fresh review"
)
elif rev_lease is None:
# Unknown lease head still must not authorize at new head.
result["reviewer_lease_superseded"] = True
reasons.append(
"any reviewer lease scoped to the former head is superseded at the new head"
)
mer_lease = _normalize_sha(former_merger_lease_head_sha)
if mer_lease and mer_lease != new:
result["merger_lease_superseded"] = True
reasons.append(
f"merger lease for head {mer_lease} cannot cross to {new}"
)
else:
result["merger_lease_superseded"] = True
reasons.append(
"any merger lease scoped to the former head is superseded at the new head"
)
prepared = _normalize_sha(prepared_verdict_head_sha)
if prepared and prepared != new:
result["prepared_verdict_invalidated"] = True
reasons.append(
f"prepared verdict for head {prepared} cannot authorize the new head {new}"
)
elif prepared is None:
result["prepared_verdict_invalidated"] = True
reasons.append(
"prepared verdicts associated with the former head are invalidated"
)
result["recommended_next_action"] = ACTION_FRESH_REVIEW_REQUIRED
reasons.append(
"route the new exact head to independent review "
f"({ACTION_FRESH_REVIEW_REQUIRED})"
)
return result
def assess_sequential_queue_step(
*,
just_merged: bool,
master_refreshed: bool,
next_pr_number: int | None = None,
) -> dict[str, Any]:
"""Controller sequential processing: reassess only after merge + master refresh."""
reasons: list[str] = []
if just_merged and not master_refreshed:
reasons.append(
"master must be refreshed after each merge before reassessing the next PR "
"(do not update every PR simultaneously)"
)
return {
"reassess_allowed": False,
"process_next": False,
"next_pr_number": next_pr_number,
"reasons": reasons,
"success": True,
}
if not just_merged:
reasons.append("no merge completed; sequential step does not advance")
return {
"reassess_allowed": False,
"process_next": False,
"next_pr_number": next_pr_number,
"reasons": reasons,
"success": True,
}
if next_pr_number:
reasons.append(
"merge completed and live master refreshed; reassess the next PR "
f"#{next_pr_number}"
)
else:
reasons.append(
"merge completed and live master refreshed; reassess the next PR"
)
return {
"reassess_allowed": True,
"process_next": True,
"next_pr_number": next_pr_number,
"post_merge_cleanup_handoff": True,
"reasons": reasons,
"success": True,
}
def merge_approval_usable_at_head(
*,
current_head_sha: str | None,
approved_head_sha: str | None,
) -> dict[str, Any]:
"""Stale approval cannot authorize merge (head-scoped only)."""
current = _normalize_sha(current_head_sha)
approved = _normalize_sha(approved_head_sha)
ok = bool(current and approved and current == approved)
reasons: list[str] = []
if not ok:
reasons.append(
f"stale approval: approved head '{approved or '(none)'}' does not "
f"match current head '{current or '(none)'}'; cannot authorize merge"
)
return {
"approval_usable": ok,
"current_head_sha": current,
"approved_head_sha": approved,
"reasons": reasons,
}
def lease_usable_at_head(
*,
lease_kind: str,
lease_head_sha: str | None,
current_head_sha: str | None,
) -> dict[str, Any]:
"""Reviewer/merger leases cannot cross heads."""
current = _normalize_sha(current_head_sha)
lease_head = _normalize_sha(lease_head_sha)
kind = (lease_kind or "").strip().lower() or "unknown"
ok = bool(current and lease_head and current == lease_head)
reasons: list[str] = []
if not ok:
reasons.append(
f"stale {kind} lease: lease head '{lease_head or '(none)'}' cannot "
f"authorize work at current head '{current or '(none)'}'"
)
return {
"lease_usable": ok,
"lease_kind": kind,
"lease_head_sha": lease_head,
"current_head_sha": current,
"reasons": reasons,
}