ci: compile fbuild once, path-selected board dispatch (badges stay current), main-only cache saves

.github/workflows/README.md

@@ -22,19 +22,27 @@ CI/CD workflows for the fbuild project, covering lint, test, documentation, and
   MSRV, board validation, and crate-gate statuses. The unselected tiers allocate no PR
   runners. The selected tier owns the Linux workspace check; when both labels
   are present, `ci-full` subsumes `ci-test`.
-- The full and nightly board matrices execute identical build inputs once.
-  Each matrix row carries `workflow_aliases` so every listed board workflow
-  remains represented, including legacy spelling aliases.
-- Per-board `build-*.yml` files are manual/reusable only. Their triggers are
-  generated by `ci/render_workflows.py`; the nightly sweep still runs every
-  board independently of PR labels.
+- The full board matrix executes identical build inputs once. Each matrix
+  row carries `workflow_aliases` so every listed board workflow remains
+  represented, including legacy spelling aliases.
+- Board jobs never compile fbuild themselves: one `fbuild_bin` job builds it
+  and uploads `fbuild-bin-linux-debug`, which `template_build.yml` downloads
+  (`fbuild-artifact` / `fbuild-run-id` inputs). Caches save only from `main`.
+- **README badges.** A badge tracks runs of its own `build-<board>.yml` file,
+  so `nightly-platforms.yml` is a dispatcher: it compiles fbuild once, then
+  `gh workflow run`s each selected board workflow with its run id. On push to
+  `main` it selects only boards whose trigger paths changed
+  (`ci/select_boards.py`: own test dir, family crate paths, own workflow file;
+  shared paths select the `core` boards); on its daily schedule it selects
+  every board (skipped when there were no commits in 24h). PRs never run the
+  full board set unless labelled `ci-full`.
 
 ## Independent lightweight checks (push/PR)
 
 - **`check-{ubuntu,windows}.yml`** -- Reusable Clippy + tests per platform (no macOS runner: macOS
   binaries are cross-built from Linux in the release matrix, see below)
-- **`fmt.yml`** -- Rustfmt check | **`docs.yml`** -- Doc build with `-D warnings`
-- **`msrv.yml`** -- MSRV 1.95.0 verification | **`validate-boards.yml`** -- Board JSON validation
+- **`fmt.yml`** -- Rustfmt check
+- MSRV 1.95.0 is the pinned toolchain (`rust-toolchain.toml` = `rust-version`, enforced by `ci/check_rust_toolchain_pins.py`), so every lane already compiles on it and there is no separate MSRV job | **`validate-boards.yml`** -- Board JSON validation
 - **`platform-boundary-research.yml`** -- Windows/Linux reconciliation of the #1307 research inventory and RED fixture
 - **`loc-gate.yml`** -- Reject `.rs` files over 1000 LOC | **`lint-subprocess.yml`** -- Forbid direct subprocess spawns
 - **`crate-gate.yml`** -- Reject new workspace crates (monocrate policy, `ci/check_workspace_crates.py`)

.github/workflows/acceptance-205.yml

@@ -73,4 +73,4 @@ jobs:
 
       - name: Run ${{ matrix.gate }} acceptance gate
         run: |
-          soldr cargo test -p fbuild-build --test ${{ matrix.test_bin }} -- --ignored --exact ${{ matrix.test_fn }} --nocapture --test-threads=1
+          soldr cargo test -p fbuild-build --test it -- --ignored --exact ${{ matrix.test_bin }}::${{ matrix.test_fn }} --nocapture --test-threads=1

.github/workflows/build-apollo3_red.yml

@@ -2,7 +2,16 @@ name: Build Apollo3 RedBoard
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -14,7 +23,11 @@ jobs:
   build:
     uses: ./.github/workflows/template_build.yml
     with:
-      workflow-name: "Apollo3 RedBoard"
+      workflow-name: "Ambiq Apollo3 Red"
       test-dir: "tests/platform/apollo3_red"
       env-name: "apollo3_red"
       firmware-ext: "bin"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-apollo3_thing_explorable.yml

@@ -2,7 +2,16 @@ name: Build Apollo3 expLoRaBLE
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -14,7 +23,11 @@ jobs:
   build:
     uses: ./.github/workflows/template_build.yml
     with:
-      workflow-name: "Apollo3 expLoRaBLE"
+      workflow-name: "Apollo3 Thing Explorable"
       test-dir: "tests/platform/apollo3_thing_explorable"
       env-name: "apollo3_thing_explorable"
       firmware-ext: "bin"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-atmega8.yml

@@ -2,7 +2,16 @@ name: Build ATmega8
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/atmega8"
       env-name: "atmega8"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-atmega8a.yml

@@ -2,7 +2,16 @@ name: Build ATmega8A
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/atmega8a"
       env-name: "atmega8a"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-attiny1604.yml

@@ -2,7 +2,16 @@ name: Build ATtiny1604
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/attiny1604"
       env-name: "attiny1604"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-attiny1616.yml

@@ -2,7 +2,16 @@ name: Build ATtiny1616
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/attiny1616"
       env-name: "attiny1616"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-attiny4313.yml

@@ -2,7 +2,16 @@ name: Build ATtiny4313
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/attiny4313"
       env-name: "attiny4313"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-attiny85.yml

@@ -2,7 +2,16 @@ name: Build ATtiny85
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/attiny85"
       env-name: "attiny85"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-attiny88.yml

@@ -2,7 +2,16 @@ name: Build ATtiny88
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/attiny88"
       env-name: "attiny88"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-blackpill.yml

@@ -2,7 +2,16 @@ name: Build BlackPill F411CE
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -14,7 +23,11 @@ jobs:
   build:
     uses: ./.github/workflows/template_build.yml
     with:
-      workflow-name: "BlackPill F411CE"
+      workflow-name: "STM32 BlackPill F411CE"
       test-dir: "tests/platform/blackpill_f411ce"
       env-name: "blackpill"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-bluepill.yml

@@ -2,7 +2,16 @@ name: Build BluePill F103C8
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -14,7 +23,11 @@ jobs:
   build:
     uses: ./.github/workflows/template_build.yml
     with:
-      workflow-name: "BluePill F103C8"
+      workflow-name: "STM32 BluePill F103C8"
       test-dir: "tests/platform/bluepill_f103c8"
       env-name: "bluepill"
       firmware-ext: "hex"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-ch32l103.yml

@@ -2,7 +2,16 @@ name: Build CH32L103
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/ch32l103"
       env-name: "ch32l103"
       firmware-ext: "bin"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false

.github/workflows/build-ch32v003.yml

@@ -2,7 +2,16 @@ name: Build CH32V003
 
 # >>> RENDERED-ON-BEGIN (ci/render_workflows.py) -- do not edit by hand <<<
 on:
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      fbuild-run-id:
+        description: 'Run holding a prebuilt fbuild artifact (empty: compile here)'
+        type: string
+        default: ''
+      checkout_ref:
+        description: 'Commit to build (empty: the dispatched ref)'
+        type: string
+        default: ''
   workflow_call: {}
 
 concurrency:
@@ -18,3 +27,7 @@ jobs:
       test-dir: "tests/platform/ch32v003"
       env-name: "ch32v003"
       firmware-ext: "bin"
+      checkout_ref: ${{ inputs.checkout_ref }}
+      fbuild-artifact: ${{ inputs.fbuild-run-id && 'fbuild-bin-linux-debug' || '' }}
+      fbuild-run-id: ${{ inputs.fbuild-run-id }}
+      toolchain-cache: false