Session Update (Checkpoint)

You are capturing work-in-progress into today's SESSION_LOG.md entry before context is cleared or handed off. The goal: preserve what THIS Claude instance knows — decisions, reasoning, blockers, dead-end approaches — before it's lost. Git alone can't recover any of that.

Primary use case: run this right before /clear. Secondary: mid-session checkpoint after a chunk of work.

Step 1: Verify Today's Entry Exists

Read .claude/SESSION_LOG.md. Find the top entry.

If top entry's date == today (MM-DD-YYYY format; legacy YYYY-MM-DD is equivalent): continue to Step 2.

If no today entry: tell the user:

"No session-start stub exists for today. Run /session-start first to create today's entry, then re-run session-update."

Stop. Do not create the entry here — that's session-start's job.

Step 2: Determine Scope of "New Work"

Look inside today's entry for a tracking marker of the form:

<!-- last-update: <git-hash> -->

• If present: new work = commits since <git-hash> + current uncommitted changes + this conversation's work not yet in the entry.
• If absent: new work = commits since today's start that aren't obviously reflected in the entry + current uncommitted changes + this conversation's work.

Collect inputs:

# Current HEAD (for the new marker)
git rev-parse --short HEAD

# Commits since last marker (if marker exists):
git log --oneline --all <marker-hash>..HEAD

# Or commits since today's start (if no marker):
git log --oneline --all --since="6am"

# Uncommitted state
git status --short
git diff --stat

Also mine this conversation's context for things git won't show:

• Decisions made and why (especially alternatives rejected)
• Approaches tried that didn't work (dead ends)
• Blockers discovered
• WIP reasoning — what was about to happen next

Step 3: Draft Section Additions

Draft bullets/rows for these four sections (merge into whatever already exists in the entry — don't replace):

### What Was Accomplished

• Numbered item per distinct accomplishment since last update
• 1 line prose + short rationale if the "why" isn't obvious from the code

### Key Decisions

• Decisions not encoded in commits (why X, not Y)
• Tradeoffs considered, options rejected

### Files Modified

• Rows for files touched since last update (use git diff --name-only <marker>..HEAD + uncommitted)

### Notes for Next Session

• WIP: uncommitted work — current state, what was about to happen next
• Blockers: issues discovered but not yet resolved
• Dead ends: approaches tried that didn't work, so the next Claude doesn't retry them

Step 4: Handle Uncommitted Work

If git diff --stat shows changes, summarize them to the user:

"Uncommitted changes: - path/to/file.py (+12 / -3) - ...

>

Capture as WIP in Notes for Next Session?"

• Yes: add a WIP bullet describing the state and intent.
• No: skip (user is mid-refactor and doesn't want noise).

Never commit the changes from this skill — WIP captures are descriptive only.

Step 5: Present Draft and Confirm

Show the user the drafted additions, grouped by section. Ask:

"Apply these updates to Session NNN? You can edit, add anything I missed, or accept as-is."

Wait for confirmation or edits. If they edit, incorporate and re-confirm.

Step 6: Merge Into Existing Entry

Read today's entry. Apply the confirmed additions using these rules:

DO NOT touch:

• The ## MM-DD-YYYY - Session NNN: [In Progress] title line
• The **Focus:** _In progress — finalize at session end_ line

Those are session-end's job to finalize.

DO:

• Insert or update the tracking marker directly under the Focus line:

  **Focus:** _In progress — finalize at session end_

  <!-- last-update: <new-HEAD-hash> -->

• For existing sections: append new items/rows (continue numbered lists from the last number).
• For missing sections: create them with the new content.
• Preserve the trailing --- separator before the next session entry.

Example — entry after first update:

## 04-13-2026 - Session 115: [In Progress]

**Focus:** _In progress — finalize at session end_

<!-- last-update: a1b2c3d -->

### What Was Accomplished

1. **Thing one** — one-line description

### Key Decisions
- Decision — rationale

### Files Modified

| File | Changes |
|------|---------|
| `api/app/foo.py` | Added bar handler |

### Notes for Next Session
- **WIP:** About to refactor `baz()` — paused here.

---

Step 7: Confirm

Tell the user:

"Session NNN updated through commit <hash>. Captured N accomplishments / M decisions / K files / [WIP: yes|no]. Safe to /clear."

Quick Reference