Memory Archive Superseded

Purpose / When to Activate

Activate when a DEC has been formally superseded by another DEC and you want to migrate its row out of the active index eager-load surface, while preserving full traceability and path stability.

Discovery-only. This skill must NEVER be invoked by daemon delivery. Per base.rules.md, Delivery may only write memory via decision-extraction after QA PASS. Archive operations are a strategic memory governance act and belong to Discovery (or Bootstrap during initialization).

When NOT to activate:

• DEC is still active or candidate (no formal supersession)
• DEC is deferred or cancelled (different lifecycle, different archive pattern)
• The supersedeur DEC is not yet active (premature archival risk)
• Pattern, ARCH, or strategy file supersession (V2 — out of scope this skill)

Preconditions (must hold before execution)

1. Supersedee DEC has frontmatter status: superseded and superseded_by: DEC-X (or [DEC-X, ...])
2. Supersedeur DEC file exists at decisions/DEC-X.md
3. Supersedeur frontmatter declares supersedes: [DEC-Y, ...] mentioning the supersedee
4. The supersedee is currently in active index.md (Active Files table and/or Decision Registry)
5. No active or in-progress backlog story is amending the supersedee DEC

If any precondition fails: STOP and escalate. Do not partial-apply.

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Process

Step 1 — Verify preconditions

Read the supersedee DEC frontmatter. Read the supersedeur DEC frontmatter. Read index.md. Read archive/superseded-decisions.archive.md. Verify all 5 preconditions above.

If status is anything other than superseded, STOP — do not flip the status as part of the archive op (that's a separate decision that requires Discovery validation).

Step 2 — Update DEC frontmatter (canonical source of truth)

For the supersedee DEC, ensure these fields are present in YAML frontmatter :

• status: superseded
• superseded_by: DEC-X (or [DEC-X, ...])
• archived_at: YYYY-MM-DD (today's date)
• archived_to: archive/superseded-decisions.archive.md

If archived_at already exists with an earlier date, leave it (idempotent — first archival date wins). If archived_to already points elsewhere, STOP — conflict requires escalation.

Step 3 — Append row to archive index

Append a row to the table under ## Superseded DEC entries in archive/superseded-decisions.archive.md. Columns :

| Supersedee | Supersedeur | Chain (if any) | Date | Original rationale | What changed | Notes |

For chains : if the supersedee was itself a supersedeur of an earlier DEC (e.g. supersedes and is itself superseded by ), render the full chain <DEC-earlier> → <DEC-id> → <DEC-later>.

Step 4 — Remove rows from active index.md

Remove the supersedee row from :

• Active Files table (the global file list)
• Decision Registry (the per-domain DEC tables)

If a row carries an inline supersession notation like ~~...~~ — superseded by DEC-X or (superseded by DEC-X), remove the entire row.

Step 5 — Add pointer row to active index "Superseded (archived)" section

If the section does not yet exist, create it after the last Decision Registry sub-table with the affordance block from the template (see "Affordance template" below).

Append a row to the pointer table :

| <supersedee> | <supersedeur> | <chain or —> | <date> | <one-line summary> |

The one-line summary should give an agent enough context to decide whether to load full files. Keep ≤120 chars.

Step 6 — Update file count metadata

Update the "Total decisions" line and Shared Categories decisions row to reflect the new active/archive split.

Step 7 — Append migration history entry

Append a row to the "Migration history" table at the bottom of archive/superseded-decisions.archive.md :

| YYYY-MM-DD | Migrate <DEC-ID> | 1 | <source> | Discovery |

Step 8 — Run linter

Run validate-memory-index.py (if shell available) OR ask another agent to run it. Linter must return CLEAN. If violations: revert the migration and escalate.

If linter is not invokable (no shell access), perform manual checks per the L3 prompt instructions in memory-index-lint/SKILL.md § "L3 In-session validation prompt".

Step 9 — Update changelog

Add an entry to index.md § Changelog summarizing the operation : DEC archived, source files touched, today's date.

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Affordance template (used in Step 5 if section does not yet exist)

### Superseded (archived)

> **How agents read this section.** Files are NOT moved — every supersedee DEC remains readable at `decisions/DEC-XX.md` (path stable). Supersession changes the file's *status*, not its *location*. For "why was X decided" questions, **read both endpoints** (supersedee + supersedeur) ; for chains, read every intermediate DEC. Use skill `memory-archive-superseded` to archive new supersedeses ; full archive rows in `archive/superseded-decisions.archive.md`.

| Supersedee | Supersedeur | Chain (if any) | Date | One-line summary |
|---|---|---|---|---|

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Idempotence & failure recovery

This skill is idempotent — running it twice on the same DEC produces no change after the first successful run. If a run fails partway :

• Frontmatter updated but archive row missing → next run detects via linter symmetry check, completes
• Archive row added but active row not removed → linter symmetry check fails, next run detects + completes
• All steps committed but linter still fails → escalate (likely upstream invariant violation)

Order of operations (frontmatter → archive → active) is chosen so that partial failure leaves a recoverable state ; rerun completes the migration.

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Migration report (inline, after completion)

# Memory Archive Superseded — {date}

## Operation
- Archived: DEC-{N} → DEC-{M}
- Chain: {chain or "—"}

## Files touched
- decisions/DEC-{N}.md (frontmatter: archived_at + archived_to added)
- index.md (rows removed from Active Files + Decision Registry, pointer appended)
- archive/superseded-decisions.archive.md (row appended)

## Linter result
- CLEAN | VIOLATIONS: ...

## Result: SUCCESS | RECOVERED | FAILED

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Quality Checks

• Idempotent — running twice on the same DEC = no-op after first successful run
• Atomicity-friendly — order frontmatter → archive index → active index so partial failures are recoverable
• Single-DEC operation by default (batch mode: invoke once per DEC sequentially, not parallel — table writes are not concurrency-safe within a single worktree)
• Skill is read-only on supersedeur DEC (only modifies supersedee + index files)
• Always validates with memory-index-lint after operation

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Non-Goals

This skill must NOT:

• Flip a DEC's status from candidate or active to superseded (that's a separate Discovery decision requiring /gaai:review-input)
• Archive patterns, ARCH files, or strategy files (V2 scope)
• Move the supersedee DEC file (path stability is hard invariant)
• Be invoked by daemon delivery
• Operate without preconditions check

memory-archive-superseded migrates an already-decided supersession. It does not make supersession decisions.

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Worktree + parallel safety

• Skill is Discovery-only — no daemon invocation paths
• Table writes are append-style → merge-friendly across worktrees
• If two parallel Discovery sessions both archive different DECs : git merge resolves cleanly (different rows)
• If two parallel sessions both archive the SAME DEC : second run is no-op (idempotent)
• No file locks required (git is the synchronization mechanism)

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Related skills

• memory-index-sync (V2 amended) — checks archived_to: field before re-adding to active registry, to prevent undo of archive
• memory-index-lint — discoverability invariants validator (L3 prompt + L4 script)
• decision-extraction — DEC creation, including supersedeur frontmatter supersedes: [...] writing