sungjunlee · sungjunlee · Jul 31, 2026 · Jul 31, 2026 · Jul 31, 2026 · Jul 31, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,7 +8,9 @@ Each entry links the GitHub issue (the canonical spec) and the merge PR (the shi
 
 ### Removed
 
-- **Monthly Progress sync and sprint issue publication** — removed 3,758 lines of scripts and dedicated tests after their intended adoption windows finished. Only one monthly issue was ever created (`Progress: April 2026`, #46; none in May–July), and the four sprint issues (#230, #234, #237, #239) were all created on 2026-07-03/04 with none since. No core lifecycle script or dev-relay integration invokes either feature, and `task-progress-reporting` accumulated no Learnings. The task mirrors under `backlog/tasks/` remain core and unchanged. Closes [#340](https://github.com/sungjunlee/dev-backlog/issues/340).
+- **Monthly Progress sync and sprint issue publication** — removed 3,758 lines of scripts and dedicated tests after their intended adoption windows finished. Only one monthly issue was ever created (`Progress: April 2026`, #46; none in May–July), and the four sprint issues (#230, #234, #237, #239) were all created on 2026-07-03/04 with none since. No core lifecycle script or dev-relay integration invokes either feature, and `task-progress-reporting` accumulated no Learnings. Closes [#340](https://github.com/sungjunlee/dev-backlog/issues/340).
+- **Required task mirrors** — the GitHub-native core now resolves task specification, AC, and lifecycle directly from live Issues. Fresh setup and complete sprint execution require no `backlog/tasks/` or `backlog/completed/`; `sync-pull --legacy-export` remains an explicit one-way diagnostic/rollback boundary. Closes [#347](https://github.com/sungjunlee/dev-backlog/issues/347).
+- **Zero-adopter local tracker and generic compatibility machinery** — measured adoption found 0 of 17 consumers selecting a non-default tracker and GitHub remotes in all 18 known consumers. The local JSON store, local lifecycle tests, and generic/local design surface are removed; GitHub failure is fail-loud with no fallback, while Backlog.md remains manual import/explicit export compatibility only. Closes [#348](https://github.com/sungjunlee/dev-backlog/issues/348).
 
 ## [0.9.0] — 2026-07-27
 
@@ -21,7 +23,7 @@ Net effect: **−2,556 lines** of scripts and tests (26,984 → 24,428) with no
 - **Local canonical store is JSON; task files become derived mirrors** (BREAKING for `tracker: local`). `backlog/local-tracker.json` is the sole local authority, and `backlog/tasks/` + `backlog/completed/` are one-way projections — exactly the role they already held in `github` mode. The binding rule: a mirror is **never** parsed back as truth, so the `tracker-task-truth` "never two co-authoritative stores" constraint is satisfied more cleanly than the shape it replaces, where Markdown was canonical *and* hand-editable *and* lock-arbitrated at once. `local-tracker.js` 1,391 → 597 lines. Closes [#321](https://github.com/sungjunlee/dev-backlog/issues/321) / PR [#327](https://github.com/sungjunlee/dev-backlog/pull/327).
 - **Concurrent-write safety is revision-based compare-and-swap, not a lock.** The store carries a monotonic `revision`; a mutation reads at N, writes a complete fsynced candidate, and claims `.local-tracker.revision-{N+1}.json` through no-overwrite `link`. A losing writer *helps the existing claim across* — it is content-complete — then re-reads and retries within a bounded budget; exhaustion fails closed rather than writing unconditionally. Crash debris is inert by construction: revision-identified files a later writer can complete or clean, never a mutual-exclusion primitive left in an unknown state.
 - **Tracker selection moves to `backlog/.tracker`**, a single line read with `readFileSync().trim()` and validated fail-closed. `config.yml` is never written again — which is what removes the reason its 395-line selection tokenizer existed. It is still *read* for its other fields through the unchanged `lib.js:parseSimpleYaml`. Legacy compatibility is exact: an existing `tracker:` key with no `.tracker` resolves as before and is migrated on the next setup run without editing `config.yml`, so the PR #301 Learning "preserve user YAML bytes" now holds permanently and trivially; a repo with neither still defaults to `github` with zero migration. `setup-dev-backlog.js` 1,007 → 567 lines. Closes [#322](https://github.com/sungjunlee/dev-backlog/issues/322) / PR [#328](https://github.com/sungjunlee/dev-backlog/pull/328).
-- **Adapter tiering and a size budget are now design contract**: a seam (`tracker.js`), remote translators (**≤200 lines**, holding no durable state), and exactly one storage substrate (`local`). The rule — *an adapter over 200 lines is not an adapter, it is a substrate; stop and re-tier* — is what keeps "support more trackers" a linear cost. Recorded in `docs/tracker-adapter-design.md` § "Adapter Tiers (v0.9.0)". Closes [#320](https://github.com/sungjunlee/dev-backlog/issues/320) / PR [#326](https://github.com/sungjunlee/dev-backlog/pull/326).
+- **Adapter tiering and a size budget are now design contract**: a seam (`tracker.js`), remote translators (**≤200 lines**, holding no durable state), and exactly one storage substrate (`local`). The rule — *an adapter over 200 lines is not an adapter, it is a substrate; stop and re-tier* — is what keeps "support more trackers" a linear cost. Recorded in the [historical v0.9.0 adapter design](https://github.com/sungjunlee/dev-backlog/blob/v0.9.0/docs/tracker-adapter-design.md) § "Adapter Tiers (v0.9.0)". Closes [#320](https://github.com/sungjunlee/dev-backlog/issues/320) / PR [#326](https://github.com/sungjunlee/dev-backlog/pull/326).
 
 ### Fixed
 
@@ -49,7 +51,7 @@ Headline: **configured tracker adapters** — exactly one adapter owns canonical
 
 ### Added
 
-- **Configured tracker adapters — one adapter owns canonical task truth per repo** (O9). A deep, capability-gated tracker seam: the active tracker is chosen only from configuration, defaults to `github` when unset, resolution probes only the configured adapter, and the runtime never silently switches trackers on failure. Required lifecycle and identity stay small; milestones, PR relationships, mirrors, progress issues, comments, and closing semantics are capability-gated and fail closed before mutation. Design frozen in `docs/tracker-adapter-design.md`. Shipped in phases:
+- **Configured tracker adapters — one adapter owns canonical task truth per repo** (O9). A deep, capability-gated tracker seam: the active tracker is chosen only from configuration, defaults to `github` when unset, resolution probes only the configured adapter, and the runtime never silently switches trackers on failure. Required lifecycle and identity stay small; milestones, PR relationships, mirrors, progress issues, comments, and closing semantics are capability-gated and fail closed before mutation. Design frozen in the [historical v0.8.0 adapter design](https://github.com/sungjunlee/dev-backlog/blob/v0.8.0/docs/tracker-adapter-design.md). Shipped in phases:
   - `tracker.js` configured-only resolver plus the core adapter seam; the `local` slot stays explicitly unavailable until the local adapter lands. Interface and `gh`-coupling inventory were frozen first. Closes [#272](https://github.com/sungjunlee/dev-backlog/issues/272) / PR [#280](https://github.com/sungjunlee/dev-backlog/pull/280) and [#273](https://github.com/sungjunlee/dev-backlog/issues/273) / PR [#282](https://github.com/sungjunlee/dev-backlog/pull/282).
   - Tracker-neutral task identity: one exact task-ref seam for GitHub `#N` and local `{PREFIX}-N[.M]`; sprint state exposes additive `tracker`/`id`/`ref` and retains GitHub `issue_number` so existing consumers keep working. Closes [#274](https://github.com/sungjunlee/dev-backlog/issues/274) / PR [#284](https://github.com/sungjunlee/dev-backlog/pull/284).
   - GitHub behind the seam: the GitHub adapter owns required lifecycle translation and confines direct `gh` calls to itself plus explicit milestone/mirror/progress/PR/comment/triage transports; core callers resolve only the configured tracker. GitHub is now the frozen compatibility baseline. Closes [#275](https://github.com/sungjunlee/dev-backlog/issues/275) / PR [#286](https://github.com/sungjunlee/dev-backlog/pull/286).
@@ -83,7 +85,7 @@ Headline: **configured tracker adapters** — exactly one adapter owns canonical
 - `skills/dev-backlog/SKILL.md` reassess-signal paragraph compressed to defer accounting details to `references/integration-contract.md`; craftkit provenance stated once per SKILL.md; stale "upcoming backlog-doctor" wording moved to present tense. Closes [#246](https://github.com/sungjunlee/dev-backlog/issues/246).
 - `skills/dev-backlog/references/integration-contract.md` component example swapped to the live `sprint-execution` slug. Closes [#248](https://github.com/sungjunlee/dev-backlog/issues/248).
 - `docs/spec-system-design.md` gains a dated provenance note for the 0.7.0 spec-* move; the dead research-survey link now cites git history (pre-`cd31a2b`) with the restore decision tracked in [craftkit#124](https://github.com/sungjunlee/craftkit/issues/124). Closes [#249](https://github.com/sungjunlee/dev-backlog/issues/249).
-- `spec/system-map.md` "Executable Evidence" now records the O8/O9 acceptance proof (PR [#303](https://github.com/sungjunlee/dev-backlog/pull/303)) as merged and both objectives `[validated]`, and adds a Project-Wide Invariant for Windows-first-class execution; the `docs/tracker-adapter-design.md` twin line is synced. Closes [#315](https://github.com/sungjunlee/dev-backlog/issues/315) / PR [#317](https://github.com/sungjunlee/dev-backlog/pull/317).
+- `spec/system-map.md` "Executable Evidence" now records the O8/O9 acceptance proof (PR [#303](https://github.com/sungjunlee/dev-backlog/pull/303)) as merged and both objectives `[validated]`, and adds a Project-Wide Invariant for Windows-first-class execution; the [historical v0.8.0 adapter design](https://github.com/sungjunlee/dev-backlog/blob/v0.8.0/docs/tracker-adapter-design.md) twin line is synced. Closes [#315](https://github.com/sungjunlee/dev-backlog/issues/315) / PR [#317](https://github.com/sungjunlee/dev-backlog/pull/317).
 - Signal-driven reassess: the post-multi-track reassess cycle ran and found no v0.8.0 release blockers (backlog-doctor 8/8, capabilities-doctor ok, component-lint clean); report `backlog/triage/2026-07-20-reassess.md`. Closes [#312](https://github.com/sungjunlee/dev-backlog/issues/312) / PR [#316](https://github.com/sungjunlee/dev-backlog/pull/316).
 
 ### Removed

diff --git a/CLAUDE.md b/CLAUDE.md
@@ -24,16 +24,17 @@ The `spec-charter`, `spec-system-map`, and `spec-grill` skills moved to [craftki
 
 - **GitHub Issues = source of truth** for task definitions (what to do)
 - **Sprint files = execution hub** (how to do it, context, notes, progress)
-- **Task files = thin GitHub mirror** (sync cache, AC checkboxes only)
-- **Backlog.md compatible** — task file format follows Backlog.md; sprints/ is a custom addition
+- **No required GitHub task mirror** — resolve task intent and AC from live Issues
+- **Legacy task export is explicit** — `sync-pull --legacy-export` is rollback/diagnostic material only
+- **Backlog.md compatible** — legacy task exports follow Backlog.md shape; sprints/ is a custom addition
 - **Cross-platform** — works on Claude Code and Codex (both have `gh` CLI)
-- **Explicit sync** — pull/push is manual; no silent background sync
+- **No hidden sync** — provider writes and legacy exports are deliberate operations
 
 ## Two-Layer Architecture
 
 ```
 GitHub (what)  ↔  gh CLI  ↔  backlog/sprints/ (how + context)
-                              backlog/tasks/   (thin mirror)
+                              backlog/tasks/   (optional legacy export)
 ```
 
 ## Project Spec Home

diff --git a/README.md b/README.md
@@ -17,18 +17,15 @@ under Upgrade behavior.
 
 README.md is the product overview and human quick start. The agent execution contract, sprint-file rules, and full script reference live in [skills/dev-backlog/SKILL.md](skills/dev-backlog/SKILL.md).
 
-The implementation still exposes local-tracker and task-export compatibility
-while the 2026-08 migration is staged. Those paths are frozen, are not the
-target product boundary, and never become co-authoritative. See the
+The zero-adopter local tracker has been removed. GitHub is the only runtime
+task authority. Backlog.md-compatible files remain an explicit one-way legacy
+import/export boundary and never become co-authoritative. See the
 [authority and routing contract](skills/dev-backlog/references/authority-contract.md).
 
 ```text
-backlog/.tracker: github | local
+backlog/.tracker: github
         |
-        +-- github -> GitHub Issues (canonical) -> no required task mirror
-        |
-        `-- local  -> backlog/local-tracker.json (canonical, no gh)
-                      -> tasks/ derived compatibility projections
+        `-- GitHub Issues (canonical) -> no required task mirror
 
 backlog/sprints/     execution hub: plan, context, progress
         ^
@@ -110,22 +107,16 @@ bash /path/to/dev-backlog/skills/dev-backlog/scripts/sprint-close.sh backlog
 Fresh GitHub setup creates only `backlog/.tracker` and `backlog/sprints/`;
 `backlog/tasks/` and `backlog/completed/` are not required or created.
 
-Transition compatibility only: an existing fully offline repository may still
-choose `--tracker local`. In that explicitly selected legacy mode,
-`backlog/local-tracker.json` remains its sole task authority; `backlog/tasks/`
-and `backlog/completed/` are derived read-only projections. Mutate the JSON
-authority only through the configured tracker lifecycle, use normalized refs
-such as `BACK-1` in the Plan, and run the same `status`, `next`, and
-`sprint-close` commands. This is separate from the GitHub-native core. Local
-mode deliberately does not invent milestones, PR relationships, comments, or closing-keyword links.
-Those requests fail before side effects with actionable remediation; JSON-capable
-commands return the same structured error contract. Do not adopt local mode for
-new repositories or add features to it during the GitHub-native migration.
+Backlog.md compatibility is a one-way legacy boundary. Import means a
+human-reviewed compatible Markdown record is used to create or amend a GitHub
+Issue. Export is the explicit `sync-pull.js --legacy-export` diagnostic or
+rollback snapshot. Runtime execution never reads task files as task truth, and
+the Backlog.md CLI or runtime is never required.
 
 For task `list`, `read`, `create`, `update`, and `close`, the stable invocation
 boundary is the configured adapter exported by `scripts/tracker.js`. Operators
 and agents resolve it with the target `backlogDir` and call those methods in
-either mode; the exact procedure and signatures are documented in
+the GitHub mode; the exact procedure and signatures are documented in
 [the process guide](skills/dev-backlog/references/process.md#required-core-lifecycle-invocation-boundary).
 
 ### Upgrade behavior
@@ -135,16 +126,17 @@ There is zero automatic tracker-selection migration. A repository with neither
 in GitHub mode with its existing `#N`, numeric `issue_number`, milestone,
 comment, and closing behavior. When `.tracker` is
 absent, runtime reads a legacy YAML selection as a compatibility fallback.
-Running `setup-dev-backlog.js` migrates that resolved choice to `.tracker`
+Only the legacy value `github` is accepted. Running `setup-dev-backlog.js`
+pins that resolved choice to `.tracker`
 without editing `config.yml`; setup never migrates task files and runtime never
 chooses a tracker from availability or failure.
 Existing automation that invokes `sync-pull.js` without a flag must add
 `--legacy-export`; otherwise the command refuses before provider access or task
 materialization. This opt-in preserves rollback/diagnostic exports without
 putting them back on the normal workflow. It is an intentional CLI migration,
 not an automatic tracker or task-data migration.
-The implementation-level contract and proof map live in
-[docs/tracker-adapter-design.md](docs/tracker-adapter-design.md).
+The retained compatibility seams, consumer evidence, and subtraction proof
+live in [docs/compatibility-subtraction.md](docs/compatibility-subtraction.md).
 
 Then use the skill during your coding session: