feat(acceptance): #205 AC#2 teensy30 AnalogOutput .dmabuffers gate

[zackees]

Summary

Closes the last unimplemented acceptance criterion of fbuild issue #205 (AC#2 from the issue body):

fbuild build teensy30 AnalogOutput -- link succeeds, .dmabuffers <= 1 KB.

• New integration test crates/fbuild-build/tests/teensy30_acceptance.rs runs the full TeensyOrchestrator against a tempdir-only AnalogOutput.ino sketch and asserts:
  • result.success (link succeeded)
  • .dmabuffers section size <= 1024 bytes (AC#2 gate)
  • No fnet_, snooze_, RadioHead, or mbedtls symbol substrings in the ELF (teensy30/LC: Teensy orchestrator compiles unreferenced framework libraries (FNET, Snooze, RadioHead, mbedtls) — causes .bss / .dmabuffers RAM overflow #204 regression guard)
  • compile_commands.json parses (via result.compile_database_path, matching the fix(acceptance): #223 stm32 SPI + teensyLC LTO-symbol probes #226 fix) and references none of FNET/Snooze/RadioHead/mbedtls
• .github/workflows/acceptance-205.yml gains a third matrix entry teensy30 AnalogOutput and the new test file is added to the pull_request.paths filter.

Why it matters

DMAMEM-tagged statics in FNET, Snooze, RadioHead and mbedtls pull DMA descriptor pools and frame buffers into the .dmabuffers section. The Teensy 3.0's 16 KB SRAM can't absorb them, so if the Phase 4/5 resolver (PR #217) regresses to linking those libraries into a simple analogWrite sketch, this gate fails the build immediately. Complements teensyLC's .bss <= 3 KB gate (#220) by exercising a second forbidden ELF section on a different MCU.

Design notes

• Uses the stm32-style inline tempdir project_dir (not the checked-in tests/platform/teensy30/ fixture) so nothing scratch lands in the repo.
• Reads result.compile_database_path directly per fix(acceptance): #223 stm32 SPI + teensyLC LTO-symbol probes #226 -- the pipeline ignores params.build_dir for compdb location.
• Skips setup/loop/analogWrite symbol probes: Release profile -flto -Os inlines them and --gc-sections strips the independent symbols (same root cause as #205 AC#4: stm32f103c8 SPI auto-discovery is failing — SPIClass symbol missing from ELF #223). Section size and forbidden-symbol substrings are the meaningful signals.

Files

• crates/fbuild-build/tests/teensy30_acceptance.rs (new, 132 LOC)
• .github/workflows/acceptance-205.yml (+4 lines: new matrix gate + paths entry)

Test plan

• uv run soldr cargo build -p fbuild-build --tests -- clean
• uv run soldr cargo clippy --workspace --all-targets -- -D warnings -- clean
• uv run soldr cargo fmt --all -- --check -- clean
• Local Windows release-mode run: deferred to CI (unrelated Windows host issue with zstd-sys / redb release builds; dev profile builds clean)
• CI Ubuntu nightly + workflow_dispatch run via the new teensy30 AnalogOutput matrix entry -- this is the canonical verification

Refs #205 -- this is one criterion of a META; AC#5 and AC#6 perf anchors remain.

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

Summary by CodeRabbit

• Tests
  • Expanded continuous integration testing for Teensy 3.0 devices by adding automated acceptance tests for analog output functionality, verifying compliance with hardware constraints and library dependency requirements.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 0e9540b4-0930-483e-812c-b28ed9750cc0

📥 Commits

Reviewing files that changed from the base of the PR and between a23d855 and 2414779.

📒 Files selected for processing (2)

• .github/workflows/acceptance-205.yml
• crates/fbuild-build/tests/teensy30_acceptance.rs

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📝 Walkthrough

Walkthrough

This PR adds a new Teensy 3.0 acceptance test for issue #205 AC#2 that validates builds using analogWrite stay within a 1 KB .dmabuffers RAM budget, contain no forbidden symbols, and exclude forbidden libraries. The CI workflow is updated to trigger and run this test on pull requests.

Changes

Teensy 3.0 AnalogOutput Acceptance Gate

Layer / File(s)	Summary
Test Documentation & Context crates/fbuild-build/tests/teensy30_acceptance.rs	Introduces acceptance test with documentation of AC#2 RAM budget gate (.dmabuffers section ≤ 1 KB) and AC#1 regression guards (forbidden symbols and libraries).
Project & Sketch Fixture crates/fbuild-build/tests/teensy30_acceptance.rs	Creates temporary PlatformIO project directory with platformio.ini for Teensy 3.0 environment and generates minimal Arduino sketch using analogWrite.
Build Configuration & Execution crates/fbuild-build/tests/teensy30_acceptance.rs	Configures BuildParams for Teensy orchestrator in Release mode with clean build, compile database generation, and verbose output; invokes build.
Memory & Symbol Validation crates/fbuild-build/tests/teensy30_acceptance.rs	Validates ELF .dmabuffers section is ≤ 1 KB, verifies absence of forbidden symbols (fnet_, snooze_, RadioHead, mbedtls), and checks compile_commands.json contains no forbidden libraries.
Workflow Configuration .github/workflows/acceptance-205.yml	Adds path trigger for test file and new job matrix entry (gate: teensy30 AnalogOutput) to run teensy30_analog_output_meets_205_ac2 test function.

Estimated Code Review Effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A little bunker in the CI, now guards the Teensy's signal high,
No forbidden symbols creep or crawl, just analogWrite within its thrall,
One kilobyte of memory's grace—a perfect RAM budget for this place! 🎶

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and specifically describes the main change: adding a new Teensy30 AnalogOutput acceptance test gate for issue #205 AC#2 that validates .dmabuffers constraints, matching the PR's primary purpose.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/205-ac2-teensy30-analog-output-gate

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