diff --git a/.github/CI.md b/.github/CI.md
new file mode 100644
index 0000000000..a5b6401b7e
--- /dev/null
+++ b/.github/CI.md
@@ -0,0 +1,88 @@
+# CI — Win-CodexBar
+
+Win-CodexBar runs one hosted workflow: the **PR check** on Blacksmith Windows.
+Release stays **local**. See `CONTEXT.md` for the shared CI budget glossary
+and `docs/adr/0001` and `docs/adr/0002` for the decisions.
+
+## Workflows
+
+### PR check — `.github/workflows/pr-check.yml`
+
+Runs on `pull_request`, on `push` to `main`/`master`, and on
+`workflow_dispatch`. Runner: `blacksmith-4vcpu-windows-2025`
+(Windows Server 2025; VS Build Tools available per Blacksmith docs).
+
+Exact commands run, in order:
+
+```powershell
+cargo fmt --all --check
+cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
+cargo clippy --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml --all-targets -- -D warnings
+cargo test --manifest-path rust/Cargo.toml
+cargo test --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml
+pnpm --dir apps/desktop-tauri test
+pnpm --dir apps/desktop-tauri run build
+```
+
+This is the **local-check slice** from `scripts/local-check.ps1` only. It does
+**not** run `tauri:build` release, installer packaging, smoke install, or
+upload. Those stay on the local release path.
+
+`concurrency.cancel-in-progress` is on, keyed by ref, so superseded pushes
+cancel the in-flight run.
+
+### Interaction guard — `.github/workflows/interaction-guard.yml`
+
+Unchanged except for the budget gate (below). Runner stays
+`blacksmith-2vcpu-ubuntu-2404`. Permissions are unchanged
+(`contents: read`, `issues: write`, `pull-requests: write`).
+
+## CI budget mode
+
+Both workflows carry the gate `if: vars.CI_BUDGET_MODE != 'off'`, so they run
+when the variable is unset (`normal`), `normal`, or `thin`, and **skip only
+when `off`**.
+
+Set `CI_BUDGET_MODE` in **Settings → Secrets and variables → Actions →
+Variables**. Do not hard-code it in a workflow.
+
+| Mode   | PR check | Interaction guard | Release |
+|--------|----------|--------------------|---------|
+| normal | runs     | runs               | local   |
+| thin   | runs     | runs               | local   |
+| off    | skip     | skip               | local   |
+
+## Intent share (60/30/10)
+
+The Blacksmith Pool minutes intent is divided: roughly **60% Win-CodexBar**,
+**30% linear-cli**, **10% buffer**. This is an intent allocation of the
+pool's minutes, not a measure of time spent in `normal`/`thin`/`off` modes.
+Win-CodexBar's single Blacksmith Windows PR check is the only recurring
+Windows job. If you add a second recurring job, reassess the 60% share before
+merging.
+
+## Blacksmith billing — Windows bills 2x
+
+On the Blacksmith **free tier**, **Windows minutes bill at 2x**: one Windows
+minute consumes two free-tier minutes. `blacksmith-4vcpu-windows-2025` is
+Windows Server 2025. Because the PR check is a thin slice (fmt + clippy +
+test) and never runs release builds, this is the only recurring Windows
+cost. Keep it that way.
+
+## $0 spend alert
+
+Treat any non-zero monthly Blacksmith bill as an alert. If spend appears:
+
+1. Set `CI_BUDGET_MODE=off` to stop both workflows immediately.
+2. Investigate which run(s) consumed minutes (Actions tab → billed runs).
+3. Trim or fix, then restore `CI_BUDGET_MODE=normal` (or `thin`).
+
+The default posture is **$0 spend**. The PR check should stay within free-tier
+minutes; if it does not, prefer reducing the check slice before paying.
+
+## Release
+
+Release is **local only**. There is no hosted release workflow. Follow
+`docs/BUILDING.md` and `docs/release/ci-cd.md`: tag, run release-doctor, run
+`windows-release-build.ps1 -SmokeInstall`, then upload assets to GitHub
+Releases manually.
diff --git a/.github/workflows/interaction-guard.yml b/.github/workflows/interaction-guard.yml
index eeafc08ecb..d44b264f9c 100644
--- a/.github/workflows/interaction-guard.yml
+++ b/.github/workflows/interaction-guard.yml
@@ -13,6 +13,7 @@ permissions:
 
 jobs:
   guard:
+    if: vars.CI_BUDGET_MODE != 'off'
     runs-on: blacksmith-2vcpu-ubuntu-2404
     steps:
       - uses: actions/checkout@v4
diff --git a/.github/workflows/pr-check.yml b/.github/workflows/pr-check.yml
new file mode 100644
index 0000000000..e4ed5ec3e7
--- /dev/null
+++ b/.github/workflows/pr-check.yml
@@ -0,0 +1,82 @@
+name: PR check
+
+on:
+  push:
+    branches: [main, master]
+    paths-ignore:
+      - 'docs/**'
+      - '**/*.md'
+      - 'CONTEXT.md'
+      - '.github/CI.md'
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - '**/*.md'
+      - 'CONTEXT.md'
+      - '.github/CI.md'
+  workflow_dispatch:
+
+concurrency:
+  group: pr-check-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  pr-check:
+    name: Local check
+    if: vars.CI_BUDGET_MODE != 'off'
+    runs-on: blacksmith-4vcpu-windows-2025
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: x86_64-pc-windows-msvc
+          components: rustfmt, clippy
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            rust
+            apps/desktop-tauri/src-tauri
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+          cache-dependency-path: apps/desktop-tauri/pnpm-lock.yaml
+
+      - name: Install frontend deps
+        run: pnpm --dir apps/desktop-tauri install --frozen-lockfile
+
+      - name: Rust format check
+        run: cargo fmt --all --check
+
+      - name: Shared Rust clippy
+        run: cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
+
+      - name: Tauri Rust clippy
+        run: cargo clippy --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml --all-targets -- -D warnings
+
+      - name: Shared Rust tests
+        run: cargo test --manifest-path rust/Cargo.toml
+
+      - name: Tauri Rust tests
+        run: cargo test --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml
+
+      - name: Frontend tests
+        run: pnpm --dir apps/desktop-tauri test
+
+      - name: Frontend type check / build
+        run: pnpm --dir apps/desktop-tauri run build
diff --git a/CONTEXT.md b/CONTEXT.md
new file mode 100644
index 0000000000..ad0f0e7881
--- /dev/null
+++ b/CONTEXT.md
@@ -0,0 +1,69 @@
+# Shared CI Budget glossary
+
+This glossary is shared with the sister repo (`linear-cli`) so operators can
+reason about CI spend across both projects with one vocabulary.
+
+## Blacksmith Pool
+
+The shared Blacksmith free-tier minute pool that both Win-CodexBar and the
+sister repo (`linear-cli`) draw from. All `blacksmith-*` runners bill against
+this one pool. The intent-share (60%) and $0 spend alert are defined against
+the combined draw on this pool, not per repo.
+
+## CI budget mode
+
+A repository variable `CI_BUDGET_MODE` controls how much CI runs per change.
+It is intentionally coarse: `normal`, `thin`, or `off`.
+
+| Mode   | PR check | Interaction guard | Release                          |
+|--------|----------|--------------------|----------------------------------|
+| normal | runs     | runs               | local (Win-CodexBar only)        |
+| thin   | runs     | runs               | local (Win-CodexBar only)        |
+| off    | **skip** | **skip**           | local (Win-CodexBar only)        |
+
+> Note: Win-CodexBar's Release is **always local** (no release workflow on
+> Blacksmith). The sister repo `linear-cli` has a Blacksmith dispatch-only
+> release workflow, so its Release column differs by design. Budget mode does
+> not gate Win-CodexBar's local release — it is operator-driven regardless of
+> mode.
+
+- `normal` — default. Unset is treated as `normal`.
+- `thin` — Win-CodexBar's PR check survives `thin`: it is the single Windows
+  Blacksmith job and stays within the 60% intent share, so it still runs. The
+  sister repo (`linear-cli`) skips its PR check entirely under `thin`
+  (`if: mode != 'off' && mode != 'thin'`); its default PR check is already a
+  single Linux-only job, so there is no matrix to trim — `thin` simply drops
+  the whole job.
+- `off` — emergency stop. Both the PR check and the interaction guard skip.
+  Use this when the bill approaches the `$0 spend` alert threshold or when a
+  runaway workflow is burning minutes.
+
+Set it in **Settings → Secrets and variables → Actions → Variables**, not in
+code. The workflows read it as `vars.CI_BUDGET_MODE`.
+
+## Intent share (60/30/10)
+
+The Blacksmith Pool minutes intent is divided: roughly **60% Win-CodexBar**,
+**30% linear-cli**, and **10% buffer**. This is an intent allocation of the
+pool's minutes, not a measure of time spent in `normal`/`thin`/`off` modes.
+Win-CodexBar's single Blacksmith Windows PR check is the only recurring
+Windows job; release builds stay local. If you add a second recurring job
+here, reassess the 60% share before merging.
+
+## Blacksmith billing note
+
+On the Blacksmith free tier, **Windows minutes bill at 2x** (one Windows
+minute consumes two free-tier minutes). `blacksmith-4vcpu-windows-2025` is a
+Windows Server 2025 runner with VS Build Tools available, so Rust + Tauri
+builds work without extra setup. The PR check is a thin slice (fmt + clippy +
+test) and never runs `tauri:build` release, installer packaging, smoke
+install, or upload.
+
+## Local check slice
+
+The PR check mirrors `scripts/local-check.ps1`'s default slice only:
+`cargo fmt --check`, `cargo clippy -D warnings` on both crates, `cargo test`
+on both crates, and the frontend `pnpm test` / `tsc --noEmit` (via
+`pnpm run build`). It deliberately excludes `tauri:build` release, the
+installer, smoke install, and release upload — those stay on the local
+Windows release path.
diff --git a/docs/BUILDING.md b/docs/BUILDING.md
index df89da4aa3..98d918c058 100644
--- a/docs/BUILDING.md
+++ b/docs/BUILDING.md
@@ -71,9 +71,10 @@ Useful release flags:
 .\scripts\release-doctor.ps1 -Version 0.27.5
 ```
 
-There is no hosted CI/CD for this repository right now. Run local checks before
-PRs; the Windows release script is the primary path for installer and portable
-artifacts.
+A hosted **PR check** runs on Blacksmith Windows for pull requests and pushes
+to `main`/`master`; see `.github/CI.md` for its scope and budget modes. The
+Windows release script remains the primary path for installer and portable
+artifacts; there is no hosted release workflow.
 
 ## macOS Windows Cross Build
 
diff --git a/docs/adr/0001-pr-check-blacksmith-local-release.md b/docs/adr/0001-pr-check-blacksmith-local-release.md
new file mode 100644
index 0000000000..875cb7f9ae
--- /dev/null
+++ b/docs/adr/0001-pr-check-blacksmith-local-release.md
@@ -0,0 +1,36 @@
+# ADR 0001: PR check on Blacksmith Windows, release stays local
+
+Date: 2026-07-24
+Status: Accepted
+
+## Context
+
+Win-CodexBar had no hosted CI. Contributors ran `scripts/local-check.ps1`
+before PRs, and the canonical release path was `scripts/windows-release-build.ps1`
+on a local Windows server. We want hosted feedback on PRs without paying for
+release-grade CI.
+
+## Decision
+
+Add a single PR check workflow (`.github/workflows/pr-check.yml`) that runs on
+**Blacksmith Windows** (`blacksmith-4vcpu-windows-2025`). It mirrors only the
+local-check slice:
+
+- `cargo fmt --all --check` (workspace)
+- `cargo clippy --all-targets -- -D warnings` on both `rust` and
+  `apps/desktop-tauri/src-tauri`
+- `cargo test` on both crates
+- `pnpm test` and `pnpm run build` (which runs `tsc --noEmit`) in
+  `apps/desktop-tauri`
+
+Release stays **LOCAL**: no release workflow on Blacksmith. `tauri:build`
+release, installer packaging, smoke install, and upload to GitHub Releases
+continue to use `scripts/windows-release-build.ps1` on the operator's Windows
+server, exactly as documented in `docs/BUILDING.md`.
+
+## Consequences
+
+- PRs get hosted fmt/clippy/test feedback on the real Windows target.
+- No release CI spend. Release remains a deliberate, operator-driven step.
+- The Blacksmith Windows runner has VS Build Tools available, so the Rust +
+  Tauri toolchain works without extra provisioning.
diff --git a/docs/adr/0002-ci-budget-modes.md b/docs/adr/0002-ci-budget-modes.md
new file mode 100644
index 0000000000..e1d7b0ae55
--- /dev/null
+++ b/docs/adr/0002-ci-budget-modes.md
@@ -0,0 +1,33 @@
+# ADR 0002: CI budget modes
+
+Date: 2026-07-24
+Status: Accepted
+
+## Context
+
+Win-CodexBar and its sister repo (`linear-cli`) share Blacksmith CI minute
+budget. We need a single, coarse control to keep spend within the 60%
+intent share and to stop runaway spend fast. Per-workflow toggles are too
+fine-grained for an emergency stop.
+
+## Decision
+
+Introduce a repository variable `CI_BUDGET_MODE` with three modes:
+`normal`, `thin`, and `off`. Unset is treated as `normal`.
+
+- **PR check** (`pr-check.yml`): runs when mode is unset, `normal`, or `thin`;
+  skips only when `off`.
+  Gate: `if: vars.CI_BUDGET_MODE != 'off'`
+- **Interaction guard** (`interaction-guard.yml`): same gate. Keeps its
+  existing `blacksmith-2vcpu-ubuntu-2404` runner.
+- **Release**: unaffected — release stays local regardless of mode.
+
+`thin` is a no-op for Win-CodexBar's PR check because it is already a single
+job (no cross-OS matrix to trim). The mode exists for parity with the sister
+repo and as a future dial if a second job is added.
+
+## Consequences
+
+- One variable controls both workflows; `off` is an immediate, full stop.
+- Operators set `CI_BUDGET_MODE` in repo Settings → Variables, not in code.
+- The glossary in `CONTEXT.md` is the shared definition across both repos.