Compact prep + come-back prompt (compact-M)

Two deliverables, in order: (1) save the full session state to a durable file, (2) print a self-sufficient come-back prompt the user can paste to resume. This skill does NOT run /compact — the user runs it after.

Distinct from handoff-M full (which briefs a fresh agent, temp doc only). Here the point is resuming this line of work after compaction/session-restart, with the user's next task driving it.

Step 1 — Save full state (durable)

Write a resume state capturing everything needed to continue:

• Goal — what this work is ultimately for (one line)
• Where we are — what's done, current position, what just happened
• Key decisions — with the load-bearing why (so they aren't re-litigated)
• Constraints / gotchas — discovered facts, dead-ends ruled out, things to avoid
• Pointers — relevant file:line, paths, PRs, tickets, queries (reference, don't paste)
• Open threads — unresolved items
• Next — the user's stated next task (verbatim from args), sharpened into concrete first steps

Location:

1. notes-M topic active → checkpoint into that topic's notes file (update ## Summary + a ## Current state entry, bump Last updated). This IS the notes-M "before /compact" checkpoint. Print the absolute path.
2. No active topic → save to the OS temp dir (e.g. compact-resume-<slug>.md), print the path, and note: "temp copy — want a versioned copy in your repo instead?" Don't block on the answer; the come-back prompt (Step 2) is self-sufficient regardless.

Redact secrets (keys, tokens, PII).

Step 2 — Print the come-back prompt

Output a single fenced block the user can copy wholesale. Make it self-sufficient — enough inline context to resume even if the saved file is gone. Sharpen the user's raw "next" into an actionable directive, not a restatement.

Resume: <one-line goal>

## Where we are
<concise state: done / current position / just happened>

## Key context
<load-bearing decisions + why · constraints · gotchas · file:line pointers>

## Skills to (re)invoke
<e.g. notes-M topic at <path>; any others in play>

## Do next
<the sharpened next task → concrete first step(s)>

Full saved state: <path>

Keep it tight — favor pointers over pasted content. After printing, tell the user they can now run /compact (or start a fresh session and paste the block).

Rules

• Come-back prompt is the primary deliverable; the saved file is the durable backup.
• Don't duplicate content that already lives in PRDs/plans/ADRs/commits — reference by path/URL.
• Sharpen "next", don't parrot it. Point to file:line, don't paste files.