Reconcile

/reconcile — Multi-Session Drift Check

When multiple agent sessions run in parallel (especially with worktrees), files drift out of sync. This skill scans for inconsistencies and proposes fixes.

Invocation: deliberately model-invocable — the scan is read-only and auto-triggering on a drift smell is the point. Anything that changes files is proposed, never applied.

Configuration

Read the optional workspace.yaml at the project root for where state lives. Below, <state_dir> and <task_file> are its resolved values; defaults are state/ and TODO.md. Full reference: docs/state-model.md.

When to Use

• After merging worktree branches back to the default branch
• When something "feels off" after parallel work
• After a crash where multiple sessions were open
• As a periodic sanity check during heavy parallel workflows

Instructions

0. Detect the default branch

git rev-parse --git-dir >/dev/null 2>&1 || { echo "not a git repository — nothing to reconcile"; exit 0; }
DEFAULT=$(git symbolic-ref --short refs/remotes/origin/HEAD 2>/dev/null | sed 's|^origin/||')
DEFAULT=${DEFAULT:-$(git remote show origin 2>/dev/null | sed -n 's/.*HEAD branch: //p')}
DEFAULT=${DEFAULT:-main}   # no remote configured — fall back and say so in the report

1. Scan recent commit history across all branches

git log --all --oneline --since="24 hours ago" --graph

Look for:

• Multiple branches touching the same files
• Commits on branches that haven't been merged
• Conflicting changes (same file modified differently on different branches)

2. Check for file-level conflicts

For each file modified on multiple branches, diff the versions:

git diff "$DEFAULT"..<branch> -- <file>

Flag files where:

• Both branches modified the same lines (merge conflict risk)
• One branch deleted what another modified
• Timestamps or "Last Updated" fields diverged

3. Check state file consistency

For the project's state files under <state_dir> (priorities, decision log, session logs) and any task file (<task_file>), check:

• Duplicate entries: same task or decision logged twice from different sessions
• Contradictory state: one session marked something complete, another added it as in-progress
• Timestamp drift: Last Updated dates that don't match the most recent actual edit (see the chain protocol in docs/state-model.md — a stacked or spliced Last Updated line is itself a drift signal)
• Orphaned references: sections referencing things removed in another session

4. Check for SSOT violations

If the project has single-source-of-truth rules (facts that should live in exactly one file):

• Scan for duplicated facts across files
• Flag any case where the same information appears in multiple locations with different values
• Check that cross-references point to files that still exist

5. Report

RECONCILE — [DATE]

BRANCHES CHECKED:
- [branch list with last commit date]

FILE CONFLICTS:
- [file] — modified on [branch1] and [branch2] — [conflict type]

STATE DRIFT:
- [issue description]

SSOT VIOLATIONS:
- [duplicated fact] — found in [file1] and [file2]

PROPOSED FIXES:
1. [fix description]

OVERALL: [CLEAN / N issues found]

6. Apply fixes (with approval only)

Present each fix individually. Wait for approval before applying. Common fixes:

• Merge the newer version of a conflicting file
• Remove duplicate entries (keep the more detailed one)
• Update timestamps to match actual last-edit dates
• Resolve SSOT violations by keeping the canonical source and updating references

Design Principles

• Read-only by default. Report, wait for approval.
• Prefer evidence of intent over recency. When two versions conflict, look at which change the surrounding work depends on (commit messages, linked edits, whether other files reference the new value). A stale session can easily produce the newer timestamp. Use recency only as a tie-breaker when intent is unreadable.
• Preserve intent. Don't auto-resolve — different sessions may have had different goals.
• Fast. Git commands and file reads only. Under 30 seconds for a full scan.