diff --git a/.backlogit/queue/003-C.md b/.backlogit/queue/003-C.md
new file mode 100644
index 0000000..ea95574
--- /dev/null
+++ b/.backlogit/queue/003-C.md
@@ -0,0 +1,45 @@
+---
+id: "003-C"
+title: "Backlogit infrastructure hygiene"
+artifact_type: chore
+status: queued
+priority: medium
+description: "Fix backlog ID namespace collision at config level and gitignore backlogit DB files. Two config-only tasks that improve tooling reliability and repository cleanliness."
+labels:
+  - "backlogit"
+  - "config"
+  - "hygiene"
+references:
+  - "docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md"
+  - "docs/decisions/2026-05-23-backlog-id-collision.md"
+  - "docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md"
+created_at: "2026-05-23T20:12:17.0000000-07:00"
+updated_at: "2026-05-23T21:17:23.0072735-07:00"
+---
+
+## Scope
+
+Two config-level fixes for backlogit infrastructure:
+
+1. **ID namespace collision fix**: Give chores a type-discriminated task naming
+   format (`{NNN}C{suffix}`) so chore task IDs never collide with feature task IDs.
+
+2. **Gitignore DB files**: Add `.backlogit/*.db` to `.gitignore` and untrack
+   `.backlogit/backlogit.db`. Keep `.backlogit/stash.jsonl` tracked.
+
+## Acceptance Criteria
+
+- New chores created after the config change get collision-free task IDs
+  (e.g., `003C.001-T`); this staged shipment's existing queue items remain
+  `003.001-T` / `003.002-T` unless a later migration is approved
+- `.backlogit/backlogit.db` does not appear in `git status`
+- `.backlogit/stash.jsonl` remains tracked
+- `backlogit doctor` passes after config change
+- CI passes (no Rust code changes)
+
+## Source Documents
+
+- Decision: `docs/decisions/2026-05-23-backlog-id-collision.md`
+- Deliberation: `docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md`
+- Plan: `docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md`
+- Compound: `docs/compound/backlogit-id-collision-archival-protocol.md`
diff --git a/.backlogit/queue/003.001-T.md b/.backlogit/queue/003.001-T.md
new file mode 100644
index 0000000..a207cfe
--- /dev/null
+++ b/.backlogit/queue/003.001-T.md
@@ -0,0 +1,36 @@
+---
+id: "003.001-T"
+title: "Gitignore backlogit DB files and untrack cached database"
+artifact_type: task
+status: queued
+priority: medium
+parent_id: "003-C"
+description: "Add .backlogit/*.db to .gitignore, run git rm --cached .backlogit/backlogit.db, verify stash.jsonl remains tracked."
+labels:
+  - "backlogit"
+  - "gitignore"
+  - "config"
+references:
+  - "docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md"
+created_at: "2026-05-23T20:12:17.0000000-07:00"
+updated_at: "2026-05-23T21:17:23.0072735-07:00"
+---
+
+## Implementation Notes
+
+1. Add a `# backlogit (tool-managed cache)` section to `.gitignore`
+2. Add rule: `.backlogit/*.db`
+3. Run `git rm --cached .backlogit/backlogit.db`
+4. Verify: `git ls-files .backlogit/stash.jsonl` still shows the file
+5. Verify: `git status` no longer shows `.backlogit/backlogit.db`
+
+## Acceptance Criteria
+
+- `.backlogit/*.db` rule exists in `.gitignore`
+- `.backlogit/backlogit.db` is untracked (does not appear in `git status`)
+- `.backlogit/stash.jsonl` remains tracked (`git ls-files` confirms)
+- `backlogit sync` succeeds after change (DB regenerates from markdown)
+
+## Execution Posture
+
+Config change — no test harness needed. Validate via git commands.
diff --git a/.backlogit/queue/003.002-T.md b/.backlogit/queue/003.002-T.md
new file mode 100644
index 0000000..2e9b398
--- /dev/null
+++ b/.backlogit/queue/003.002-T.md
@@ -0,0 +1,47 @@
+---
+id: "003.002-T"
+title: "Fix chore task ID namespace with type-discriminated format"
+artifact_type: task
+status: queued
+priority: medium
+parent_id: "003-C"
+description: "Modify .backlogit/config.yaml chore name_format to use type-discriminated prefix so chore task IDs do not collide with feature task IDs, after confirming config.yaml is the authoritative artifact-type config."
+labels:
+  - "backlogit"
+  - "config"
+  - "id-collision"
+references:
+  - "docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md"
+  - "docs/decisions/2026-05-23-backlog-id-collision.md"
+created_at: "2026-05-23T20:12:17.0000000-07:00"
+updated_at: "2026-05-23T21:17:23.0072735-07:00"
+---
+
+## Implementation Notes
+
+1. Confirm the target file before editing: inspect `.backlogit/config.yaml` or use
+   `backlogit_get_metadata_catalog` to verify it defines
+   `artifact_types.chore.name_format`; `.backlogit/config.yml` is generated
+   autoharness metadata and does not control artifact ID formatting
+2. Edit `.backlogit/config.yaml` — change chore `name_format` from `'{NNN}{suffix}'`
+   to `'{NNN}C{suffix}'`
+3. Run `backlogit doctor` to validate no parse errors
+4. Create a test chore item to verify new ID format (e.g., `003C-C` or similar)
+5. Verify existing archived items remain accessible
+6. If backlogit rejects the format: fall back to a `prefix: C` approach or
+   consult backlogit documentation for supported format tokens
+
+## Acceptance Criteria
+
+- `.backlogit/config.yaml` is confirmed as the authoritative file for
+  `artifact_types.chore.name_format`
+- `.backlogit/config.yaml` chore section uses type-discriminated naming
+- `backlogit doctor` reports no errors
+- New chore items get IDs that cannot collide with feature IDs
+- Existing queue and archive items remain queryable
+- The compound learning `backlogit-id-collision-archival-protocol.md` must be
+  marked as superseded once the fix is validated
+
+## Execution Posture
+
+Migration-first — apply config change, then validate with doctor and a test create.
diff --git a/.backlogit/queue/005-S.md b/.backlogit/queue/005-S.md
new file mode 100644
index 0000000..cc4a988
--- /dev/null
+++ b/.backlogit/queue/005-S.md
@@ -0,0 +1,58 @@
+---
+id: "005-S"
+title: "Backlogit infrastructure hygiene"
+artifact_type: shipment
+status: queued
+priority: medium
+description: "Ship backlogit config hygiene: gitignore DB files + fix chore task ID namespace collision."
+labels:
+  - "backlogit"
+  - "config"
+  - "hygiene"
+references:
+  - "docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md"
+created_at: "2026-05-23T20:12:17.0000000-07:00"
+custom_fields:
+  items:
+    - 003-C
+    - 003.001-T
+    - 003.002-T
+updated_at: "2026-05-23T21:17:23.0072735-07:00"
+---
+
+## Manifest
+
+| Order | Item ID | Title | Type |
+|---|---|---|---|
+| 1 | 003-C | Backlogit infrastructure hygiene | chore |
+| 2 | 003.001-T | Gitignore backlogit DB files and untrack cached database | task |
+| 3 | 003.002-T | Fix chore task ID namespace with type-discriminated format | task |
+
+## Execution Notes
+
+- **Suggested order**: 003.001-T first (gitignore — lower risk, cleans working tree),
+  then 003.002-T (config change — requires validation)
+- **Branch name**: `chore/backlogit-infra-hygiene`
+- **No Rust code changes** — CI gates (fmt, clippy, test, build) should pass trivially
+- **Working tree prep**: The dirty `.backlogit/backlogit.db` will be resolved by
+  task 003.001-T itself (git rm --cached); stage the stash.jsonl change as part of
+  the branch setup commit
+
+## Pre-Ship Gate Considerations
+
+1. **Dirty working tree**: `.backlogit/backlogit.db` (modified) and
+   `.backlogit/stash.jsonl` (modified) are currently dirty. Ship should:
+   - Commit stash.jsonl changes (legitimate tracked state) on the feature branch
+   - Task 003.001-T will handle untracking the DB file
+2. **Prior 004-S local-only memory artifact** should stay out of this shipment
+   PR; it belongs to the prior 004-S closure and should not block or
+   contaminate this chore
+3. **backlogit doctor validation**: Must run after 003.002-T to confirm the config
+   change is accepted
+
+## Source Documents
+
+- Deliberation: `docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md`
+- Plan: `docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md`
+- Prior decision: `docs/decisions/2026-05-23-backlog-id-collision.md`
+- Stash entry: `E1B44C77`
diff --git a/.backlogit/stash.jsonl b/.backlogit/stash.jsonl
index 0e85204..1e79bdc 100644
--- a/.backlogit/stash.jsonl
+++ b/.backlogit/stash.jsonl
@@ -24,4 +24,4 @@
 {"id":"F3A12B91","priority":"low","kind":"task","text":"Decouple YamlValue from the public API surface in yaml_provider: the pub use serde_yaml_ng::Value as YamlValue re-export and the options: BTreeMap<String, YamlValue> public struct field in schema.rs bind the crate public API to a concrete YAML library type. Fix requires an associated type on YamlProvider or an opaque wrapper type with a migration path for callers. Source: PR #6 Copilot review thread PRRT_kwDOQEGgTs6EOIPy — docs/closure/001-S post-merge closure will reference.","created_at":"2026-05-22T20:11:00Z"}
 {"id":"C1E4F807","priority":"low","kind":"task","text":"ADR-001 Decision paragraph line-length formatting polish: the paragraph added in PR #6 commit 2106061 has inconsistent line wrapping (long lines with multiple sentences). Reformat to ~80-100 char lines for consistency with the rest of the ADR. Source: PR #6 Copilot review thread PRRT_kwDOQEGgTs6EOh6n.","created_at":"2026-05-22T20:40:00Z"}
 {"id":"F2454A73","priority":"low","kind":"task","text":"Raise CI coverage threshold above 60%: current line coverage exceeds 60%. Measure baseline, then raise COVERAGE_THRESHOLD in .github/workflows/ci.yml env block incrementally (70%, 80%) as the test suite stabilises. Source: docs/closure/2026-05-23-003-S-closure.md","created_at":"2026-05-23T00:13:42Z"}
-{"id":"E1B44C77","priority":"medium","kind":"chore","text":"Fix backlog ID namespace collision at config level: modify backlogit config.yaml so chores use a type-discriminated task naming format (e.g., 002C.001-T) to avoid clashing with feature task IDs when parent NNN values match. Until then, colliding queue task files must be deleted (not archived) at shipment close time. Source: docs/decisions/2026-05-23-backlog-id-collision.md","created_at":"2026-05-23T22:31:00Z"}
+{"id":"E1B44C77","priority":"medium","kind":"chore","text":"Fix backlog ID namespace collision at config level: modify backlogit config.yaml so chores use a type-discriminated task naming format (e.g., 002C.001-T) to avoid clashing with feature task IDs when parent NNN values match. Until then, colliding queue task files must be deleted (not archived) at shipment close time. Source: docs/decisions/2026-05-23-backlog-id-collision.md","created_at":"2026-05-23T22:31:00Z","state":"harvested","harvested_to":"003-C"}
diff --git a/docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md b/docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md
new file mode 100644
index 0000000..eeac806
--- /dev/null
+++ b/docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md
@@ -0,0 +1,114 @@
+---
+title: "Backlogit Infrastructure Hygiene"
+type: deliberation
+description: "Deliberation on grouping backlog ID namespace fix with gitignore hygiene for backlogit DB files"
+topic: "Backlogit config-level fixes: ID namespace collision + gitignore DB files"
+depth: "lightweight"
+stash_ids:
+  - "E1B44C77"
+promote_to: "plan"
+created: 2026-05-24
+linked_artifacts:
+  - "docs/decisions/2026-05-23-backlog-id-collision.md"
+  - "docs/compound/backlogit-id-collision-archival-protocol.md"
+tags:
+  - "backlogit"
+  - "config"
+  - "gitignore"
+  - "chore"
+---
+
+## Problem Frame
+
+Two backlogit infrastructure issues require config-level fixes:
+
+1. **ID namespace collision** (`E1B44C77`): Features and chores share a single
+   `{NNN}` sequence counter. When both hit the same counter value, their child
+   tasks produce identical IDs (`001.001-T` under both `001-F` and `001-C`).
+   The workaround (delete-not-move on archival) is documented but fragile. The
+   root fix is type-discriminated task naming for chores.
+
+2. **Gitignore gap** (operator instruction): `.backlogit/backlogit.db` is a
+   tool-managed SQLite cache that should not be tracked in git. It appears as
+   dirty working tree noise and risks merge conflicts. The stash file
+   (`.backlogit/stash.jsonl`) is intentionally tracked state and must remain so.
+
+**Who cares**: Ship agent (archival correctness), all agents (clean `git status`),
+operator (repository hygiene).
+
+**Success criteria**: Chore tasks get collision-free IDs; backlogit DB files are
+gitignored; stash.jsonl remains tracked.
+
+## Research Findings
+
+* The existing decision document (`2026-05-23-backlog-id-collision.md`) confirms
+  the root cause and recommends type-discriminated prefixes for chore tasks.
+* The compound learning (`backlogit-id-collision-archival-protocol.md`) documents
+  the interim workaround and explicitly references `E1B44C77` as the long-term fix.
+* Current `config.yaml` uses `name_format: '{NNN}{suffix}'` for all types —
+  chores get `{NNN}-C` and their tasks inherit the same `{NNN}` as features.
+* Current `.gitignore` has no rules for `.backlogit/` database files.
+* `.backlogit/backlogit.db` is currently tracked (shows as modified in
+  `git status`).
+
+## Options Evaluated
+
+### Option A: Combined chore — config fix + gitignore in one release unit
+
+Both changes target the same infrastructure surface (`.backlogit/` and
+`.gitignore`), require no Rust source changes, and form a coherent "backlogit
+hygiene" chore. Ship them together.
+
+* **Pros**: Single PR, coherent scope, fast turnaround, unblocks Ship immediately
+* **Cons**: None significant — both are small config changes
+* **Effort**: Low (2 tasks × ~1 hour each)
+* **Fit**: Excellent — both are medium-priority config hygiene
+
+### Option B: Separate chores — one for ID fix, one for gitignore
+
+Stage each as its own chore with its own shipment.
+
+* **Pros**: Maximum isolation
+* **Cons**: Unnecessary overhead for two tiny changes that share the same surface;
+  doubles PR review cost; both are prerequisite hygiene for future work
+* **Effort**: Same total effort but double coordination cost
+* **Fit**: Poor — artificially splitting coherent work
+
+## Trade-off Comparison
+
+| Criterion | Option A (Combined) | Option B (Separate) |
+|---|---|---|
+| Coherence | High — same domain | Low — artificial split |
+| PR overhead | 1 PR | 2 PRs |
+| Risk | Low | Low |
+| Ship turnaround | Fast | Slower |
+| Unblock value | Immediate | Delayed |
+
+## Decision
+
+**Option A: Combined chore.** Ship both fixes as a single "Backlogit
+Infrastructure Hygiene" chore with two tasks. The scope is tight, the blast
+radius is config-only, and both changes serve the same operational goal:
+make backlogit tooling work cleanly without workarounds.
+
+## Rejected Alternatives
+
+Option B rejected: no benefit to splitting two small, tightly related config
+changes into separate release units.
+
+## Unresolved Questions
+
+* The config.yaml change for type-discriminated task naming depends on whether
+  the current backlogit version supports format tokens like `{parent_NNN}C` or
+  whether a simpler approach (separate counter per type) is needed. The impl-plan
+  must investigate this.
+* Whether `.backlogit/backlogit.db` needs `git rm --cached` to stop tracking it
+  (likely yes, since it currently shows as modified).
+
+## Risks and Mitigations
+
+| Risk | Mitigation |
+|---|---|
+| Config change breaks existing task ID parsing | Validate with `backlogit doctor` after change |
+| Gitignore change loses stash.jsonl tracking | Explicitly verify stash.jsonl is NOT matched by the new rule |
+| Existing archived items with old IDs become orphaned | No impact — archived items retain their IDs; only new chore tasks get new format |
diff --git a/docs/memory/2026-05-24/stage-005-s-assembly-memory.md b/docs/memory/2026-05-24/stage-005-s-assembly-memory.md
new file mode 100644
index 0000000..c7ee2e8
--- /dev/null
+++ b/docs/memory/2026-05-24/stage-005-s-assembly-memory.md
@@ -0,0 +1,47 @@
+---
+type: session-memory
+agent: stage
+date: 2026-05-24
+session: stage-005-s-assembly
+status: complete
+---
+
+## Session Summary
+
+Staged shipment `005-S` from stash entry `E1B44C77` + operator gitignore instruction.
+
+## Artifacts Created
+
+| Type | Path |
+|---|---|
+| Deliberation | `docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md` |
+| Plan | `docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md` |
+| Chore | `.backlogit/queue/003-C.md` |
+| Task 1 | `.backlogit/queue/003.001-T.md` |
+| Task 2 | `.backlogit/queue/003.002-T.md` |
+| Shipment | `.backlogit/queue/005-S.md` |
+
+## Stash Entries Consumed
+
+- `E1B44C77` → harvested to `003-C`
+
+## Deferred Entries (26 remaining)
+
+All other stash entries remain active. Medium-priority candidates for next session:
+- `DDF819E0` (manifest command), `7B611B73` (MCP tools), `C7AA4D4B` (join command)
+- `B821FFFD`, `3AF98027`, `C60FFBA9` (medium tasks — potential grouped batch)
+
+## Decisions
+
+- Combined gitignore + ID collision into single chore (tight domain coherence)
+- Plan review: PASS with no blocking findings
+- Execution order: gitignore first (003.001-T), then config fix (003.002-T)
+
+## Ship Pre-Conditions
+
+1. Dirty working tree needs cleanup before Ship claims 005-S
+2. Any local-only 004-S closure memory artifact should stay out of this
+   shipment PR; it belongs to the prior 004-S closure and should not block or
+   contaminate this chore
+3. `.backlogit/stash.jsonl` changes should be committed (legitimate tracked state)
+4. backlogit doctor validation required after 003.002-T
diff --git a/docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md b/docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md
new file mode 100644
index 0000000..a01b095
--- /dev/null
+++ b/docs/plans/2026-05-24-backlogit-infra-hygiene-plan.md
@@ -0,0 +1,213 @@
+---
+title: "Backlogit Infrastructure Hygiene — Implementation Plan"
+type: impl-plan
+date: 2026-05-24
+source: "docs/decisions/2026-05-24-backlogit-infra-hygiene-deliberation.md"
+parent_decision: "docs/decisions/2026-05-23-backlog-id-collision.md"
+stash_ids:
+  - "E1B44C77"
+status: reviewed
+---
+
+## Problem Frame
+
+Two config-level issues in backlogit tooling infrastructure require fixes:
+
+1. **ID namespace collision**: `config.yaml` assigns all level-1 types from a shared
+   `{NNN}` counter. Chore tasks inherit the parent's `{NNN}`, colliding with feature
+   tasks when counter values match. File: `.backlogit/config.yaml`, which is the
+   backlogit artifact-type config; `.backlogit/config.yml` is a generated
+   autoharness metadata file and does not define `artifact_types.*.name_format`.
+
+2. **Untracked DB file pollution**: `.backlogit/backlogit.db` is a disposable SQLite
+   cache managed by the backlogit tool. It should not be tracked in git. It currently
+   shows as modified in `git status`, creating noise. File: `.gitignore`.
+
+Neither change touches Rust source code. Both are config/repo-hygiene only.
+
+## Requirements Trace
+
+| Requirement | Implementation Unit |
+|---|---|
+| Chore tasks get collision-free IDs | Unit 1: Config change |
+| backlogit DB files are gitignored | Unit 2: Gitignore + untrack |
+| stash.jsonl remains tracked | Unit 2: Verify exclusion |
+| Existing archived items unaffected | Unit 1: Validate with doctor |
+
+## Implementation Units
+
+### Unit 1: Fix chore task ID namespace in config.yaml
+
+**What**: Modify `.backlogit/config.yaml` to give the `chore` artifact type a
+type-discriminated task naming format that avoids collisions with feature task IDs.
+Target `.backlogit/config.yaml` because it is the file that defines
+`artifact_types.chore.name_format`; `.backlogit/config.yml` only carries generated
+prefix/status metadata.
+
+**Approach**: Change the chore `name_format` from `'{NNN}{suffix}'` to
+`'{NNN}C{suffix}'` so newly created chores get IDs like `003C-C` and newly
+created child tasks become `003C.001-T` instead of `003.001-T`. This staged
+shipment already contains queue artifacts created under the old format
+(`003-C`, `003.001-T`, `003.002-T`); this PR does not rename or migrate those
+existing IDs. This is the simplest change that breaks the collision for future
+items without requiring backlogit code changes — the `{NNN}` token already
+supports alphanumeric suffixes in the format string.
+
+If backlogit's ID parser rejects the `C` infix (validation step), fall back to
+using a higher counter offset or a separate `chore_counter_start` field if
+supported. The Ship agent should validate by running `backlogit doctor` after the
+config change.
+
+**Files affected**:
+- `.backlogit/config.yaml` (1 line change in chore section)
+
+**Tests/Verification**:
+- Confirm the target file with `backlogit_get_metadata_catalog` or direct config
+  inspection: `.backlogit/config.yaml` contains `artifact_types.chore.name_format`,
+  while `.backlogit/config.yml` does not
+- Run `backlogit doctor` to confirm no parse errors
+- Create a test chore item and verify its ID does not collide with existing feature IDs
+- Verify existing queue and archive items remain accessible
+
+**Execution posture**: Migration-first (config change, then validate)
+
+**Acceptance criteria**:
+- `backlogit doctor` reports no errors after config change
+- New chore items created after the config change get IDs like `003C-C`
+  (type-discriminated)
+- Existing items (`001-F`, `002-F`, archived tasks) remain queryable
+
+---
+
+### Unit 2: Gitignore backlogit DB files and untrack the cached database
+
+**What**: Add a gitignore rule for backlogit database files and remove
+`.backlogit/backlogit.db` from git tracking. Ensure `.backlogit/stash.jsonl`
+remains tracked.
+
+**Approach**:
+1. Add rule `.backlogit/*.db` to `.gitignore` (under a new `# backlogit` section)
+2. Run `git rm --cached .backlogit/backlogit.db` to stop tracking the file
+3. Verify `.backlogit/stash.jsonl` is NOT matched by the new rule
+4. Commit both changes together
+
+**Files affected**:
+- `.gitignore` (add 3 lines: comment + rule + blank line)
+- `.backlogit/backlogit.db` (untrack only — file remains on disk)
+
+**Tests/Verification**:
+- `git status` no longer shows `.backlogit/backlogit.db` as modified
+- `git ls-files .backlogit/stash.jsonl` still shows the file as tracked
+- `backlogit sync` still works (the DB is regenerated from markdown files)
+
+**Execution posture**: Config change (no test harness needed — repo metadata only)
+
+**Acceptance criteria**:
+- `.backlogit/backlogit.db` does not appear in `git status` after commit
+- `.backlogit/stash.jsonl` remains tracked (`git ls-files` confirms)
+- `backlogit sync` succeeds on a fresh clone (DB is ephemeral cache)
+
+## Dependency Graph
+
+```text
+Unit 1 (config.yaml) ──┐
+                        ├──► Ship PR (single branch, single commit set)
+Unit 2 (gitignore)   ──┘
+```
+
+Units are independent — no ordering dependency between them. Both can be
+implemented in any order or in a single commit sequence. Unit 2 is slightly
+lower risk and can serve as a confidence-building first commit.
+
+Suggested execution order: Unit 2 first (gitignore), then Unit 1 (config).
+
+## Decisions and Rationale
+
+| Decision | Rationale |
+|---|---|
+| Use `{NNN}C{suffix}` format for chores | Simplest discriminator; no backlogit code change needed if format tokens accept literal chars |
+| Gitignore `*.db` pattern under `.backlogit/` | Covers any future DB files; more robust than targeting a single filename |
+| `git rm --cached` for untracking | Preserves the local file while removing from index — standard git workflow |
+| Keep stash.jsonl tracked | Operator instruction; stash is legitimate state, not cache |
+
+## Risks and Caveats
+
+| Risk | Likelihood | Impact | Mitigation |
+|---|---|---|---|
+| Backlogit rejects `{NNN}C{suffix}` format token | Low | Blocks Unit 1 | Validate immediately; if rejected, use `prefix: C` approach or separate counter |
+| `git rm --cached` on a shared branch causes confusion | Very low | Low | Document in commit message; file stays on disk |
+| Future backlogit upgrade changes config schema | Low | Low | Pin to documented schema version |
+
+## Plan Hardening Signals
+
+* public API, schema, or contract change — **Absent** (internal tooling config only)
+* security, auth, permission, or compliance-sensitive behavior — **Absent**
+* migration, backfill, destructive data/config action, or irreversible step — **Present**
+  (`git rm --cached` is a destructive git-index action, even though it is reversible via `git add`)
+* external integration, operator checkpoint, or external dependency — **Present**
+  (Unit 2 requires an explicit operator checkpoint before `git rm --cached`)
+* high runtime, rollout, or rollback risk — **Absent** (config-only, no production code)
+
+Requires plan hardening: yes
+
+## Runtime Verification and Closure
+
+Neither unit changes a runtime surface (no CLI behavior, no API, no production code).
+
+Verification is limited to:
+- `backlogit doctor` passes after config change (Unit 1)
+- `git status` is clean after gitignore change (Unit 2)
+- CI passes (fmt, clippy, test, build are unaffected by config changes)
+
+No monitoring plan, rollback trigger, or observation window is required — this
+is pure repository metadata hygiene with no runtime impact.
+
+## Constitution Check
+
+| Principle | Compliance |
+|---|---|
+| I. Safety-First Rust | N/A — no Rust code changes |
+| II. Test-First Development | N/A — no production code; validation via `backlogit doctor` |
+| III. Workspace Isolation | Compliant — all changes within workspace |
+| IV. CLI Containment | Compliant |
+| VII. Destructive Command Approval | Compliant — Unit 2 requires an explicit operator approval/checkpoint before `git rm --cached` |
+| IX. Git-Friendly Persistence | Compliant — YAML config, gitignore are mergeable text |
+| XI. Merge Commit History | Ship will use merge commit |
+
+## Plan Hardening
+
+Hardening is required because Unit 2 contains a destructive git-index action (`git rm --cached .backlogit/backlogit.db`) that alters VCS history and is therefore subject to Constitution Principle VII (Destructive Command Approval).
+
+**Risky action**: `git rm --cached .backlogit/backlogit.db`
+
+**Risk classification**: `destructive` — modifies the git index on a shared branch; the file is removed from tracking even though it remains on disk.
+
+**Approval required**: Yes — operator must explicitly confirm before the Ship agent executes this command.
+
+**Rollback**: `git add .backlogit/backlogit.db` restores tracking; the file is never deleted from disk.
+
+**Operator checkpoint**: Ship agent MUST pause before Unit 2 execution and obtain explicit operator approval. The `.gitignore` change (Unit 2, step 1) may be applied first without approval; only the `git rm --cached` step requires the checkpoint.
+
+**Execution detail added**: Unit 2 step sequence clarified — add `.gitignore` rule first, then request approval, then run `git rm --cached`, then commit both changes together.
+
+## Plan Review
+
+**Gate decision: PASS**
+
+**Reviewed by**: Constitution Reviewer, Rust Reviewer, Scope Boundary Auditor,
+Learnings Researcher, Architecture Strategist
+
+**Plan hardening required**: Yes (Unit 2 requires an explicit operator checkpoint before `git rm --cached`)
+
+### Findings
+
+| Severity | Finding | Recommendation |
+|---|---|---|
+| P3 | Unit 1 fallback if backlogit rejects `{NNN}C{suffix}` format | Already documented in Risks section — no action needed |
+
+### Verdict
+
+Plan is well-scoped, config-only, and aligned with the existing decision document
+and compound learning. No blocking findings. Approved for harvest.
+
+<!-- plan-review-attempt: 1 -->