fix: SDK compiler defaults, library extraction, and Windows esptool

[zackees]

Summary

Refs #1677. Coordinated with FastLED/FastLED#4831; this dependency must be published before the final FastLED pin and validation.

• Read Pico SDK SdFat defaults from platform.txt, preserving board overrides and existing networking flags.
• Archive selected local and optional framework library objects on Teensy/Pico with the real LTO-aware archiver. Mandatory core and support objects stay direct. Ordinary archive groups preserve references to earlier dependencies without retaining unused members.
• Invalidate firmware built with the previous compiler-default or linking policy.
• On Windows, route recognized pioarduino registry esptool packages to the published source archive at the pinned version. Reuse the existing UV installer and runtime version checks; preserve direct source URLs and legacy packages.
• Bump the release candidate to 2.5.41. Extend existing Ubuntu and Windows workflows and the local replay inventory; no new workflows.

RED → GREEN evidence

• Actual Pico SDFS.cpp failed with a private copy constructor; SDK-defined flags compile it for RP2040 and RP2350. Real downstream Blink builds also pass for Pico, Pico 2 and XRP.
• Actual Teensy 4.1 Blink flash was 73,728 bytes against a 50,176-byte limit; corrected candidate is 47,104 bytes and passes its unchanged bloat budget. Teensy 4.0 and LC also passed their existing checks during integration.
• Actual RP2040 image failed at 172,348 bytes. SDK-only archiving reduced it to 146,952 but still failed; proper local/SDK extraction reaches 103,328 image bytes and 8,636 attributed RAM, passing unchanged 135,744/9,474 ceilings.
• Real Pico FxSdCard and Teensy OctoWS2811 examples build and link with the completed archive implementation.
• Real GCC regressions first reproduced unused constructor retention and backward archive dependency failure; both now execute successfully, preserving required constructors and excluding unused ones. Existing Ubuntu CI explicitly runs them.
• Persisted fingerprint regressions prove old defaults/linkage rebuild and current records remain reusable.
• Native Windows integration returned 404 for the synthesized esptool 5.1.0 binary. The published SDK descriptor instead names a source archive; its downloaded SHA-256 was verified. URL/version tests pass, and existing Windows CI now requires actual cold 5.1.0 installation plus warm recheck, alongside the existing legacy 3.3 test.

Validation status

• 308 library unit tests pass.
• 20 workflow tests and rendered workflow drift checks pass.
• Focused native GCC and cache-policy tests pass; independent review is clean.
• Official source-bound local gate passed in 949 seconds: Linux guards, workspace Clippy/tests, Python facade, real native linker regressions, and Dylint. The gate automatically attested tree ca323e0a2653fd885a7a06dc0d9c9ddc1c7dfacf on commit f27d10de366b43007c9a0c121c04c64ca6b452f5. That candidate passed the hosted board matrix, both native GCC regressions, Apple Silicon tests, both Mac wheel smokes, and real Windows legacy/5.1 cold/warm installer tests. Intel exposed a concurrency test that assumed subprocess startup within300ms. A reviewed follow-up uses explicit Tokio start/completion signals while preserving overlap, serialization, and maximum-concurrency assertions; a deliberate400ms startup delay reproduced RED and now passes five iterations. The follow-up official gate passed in674 seconds (Linux396s, Dylint277s), automatically attesting commit b40617fe62c2bf5919e039399efb7ac0c10e38d3, tree 29ce8632be0b. That exact candidate passed all 121 hosted PR checks (six optional jobs skipped), the release dry run, and publication. All five platform wheels are published as 2.5.41. The earlier dry run was cancelled as superseded, not counted as a pass.
• Review found stale editable-package metadata in uv.lock. Commit a7bff04b0937414e76c08d0fe9f9cc44991e0f3b corrects only that version; uv lock --check and the official local gate pass (754 seconds). Its fresh full hosted CI and CodeRabbit review passed; merged as dc87035e2819. Published release code remains b40617fe62.
• FastLED with the installed PyPI wheel provisions all three ESP AST SDKs and passes all 138 AST jobs. Manual Pico, Teensy 4.1 and ESP32-S3 Blink builds and unchanged image/RAM budgets pass. All downstream board builds and size gates passed on FastLED head 651868a467, including Pico/Pico 2/XRP, Teensy, OctoWS2811, and Windows real ESP provisioning.

No size budgets, SDK versions, or source-analysis checks were weakened. Published-wheel downstream acceptance is verified; #1677 is resolved.

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Reviewing files that changed from the base of the PR and between f27d10d and a7bff04.

⛔ Files ignored due to path filters (1)

• uv.lock is excluded by !**/*.lock

📒 Files selected for processing (1)

• crates/fbuild-build-engine/src/pipeline/library_shared_gate_tests.rs

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📝 Walkthrough

The pull request changes optional library linking for RP2040 and Teensy builds, adjusts Windows esptool source selection and CI checks, and updates the workspace and Python project versions to 2.5.41.

Changes: Optional library linkage

Layer / File(s)	Summary
Optional object archiving crates/fbuild-build-engine/src/pipeline/*, .github/workflows/check-ubuntu.yml, local-gate.toml	The build pipeline accepts optional framework sources and archives their objects with local-library objects. The archive helper checks that requested objects are present. Native-GCC tests and Ubuntu checks cover optional-library linkage. The shared-gate test uses notifications to coordinate core and library compilation.
RP2040 and Teensy build integration crates/fbuild-build-arm/src/rp2040/orchestrator.rs, crates/fbuild-build-arm/src/teensy/orchestrator.rs	Both orchestrators pass framework sources to the optional-library pipeline and record linkage policy in build fingerprints. RP2040 also applies platform SdFat definitions and tests platform defaults, board overrides, and SDK SDFS compilation.
Teensy archive rescanning crates/fbuild-build-arm/src/teensy/teensy_linker.rs	Teensy link arguments group archives and libraries. An ignored native-GCC test checks linking when a later archive references an earlier dependency archive.

Windows esptool source installation

Layer / File(s)	Summary
Host-aware esptool source resolution crates/fbuild-library/src/library/esptool.rs, crates/fbuild-library/src/library/esptool_tests.rs	Matching Windows registry URLs select the pioarduino source archive. Tests cover Windows and Unix metadata, direct archive URLs, and legacy payloads.
Windows installation checks .github/workflows/check-windows.yml, ci/test_fractional_workflows.py	A Windows workflow checks cold and warm esptool 5.1.0 installs for ESP32-C6. A workflow contract test checks the runner, install calls, and result validation.

Package version update

Layer / File(s)	Summary
Version metadata Cargo.toml, pyproject.toml	Both project version values change from 2.5.40 to 2.5.41.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Orchestrator as RP2040 or Teensy orchestrator
  participant Pipeline as run_sequential_build_with_optional_framework_libs
  participant ArchiveHelper as archive_optional_library_objects
  participant Archiver
  Orchestrator->>Pipeline: Pass framework sources and library build environment
  Pipeline->>ArchiveHelper: Pass optional object paths and link inputs
  ArchiveHelper->>Archiver: Create or update libOptionalLibraries.a

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Merge Risk: ⚪ Minimal · up to a7bff

The updated shared-gate test synchronizes the core and library phases with notifications. No actionable merge-blocking risk is evident in the reviewed change.

Pre-merge checks · 4 · 1

Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 70.27% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 37 functions across 9 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely summarizes the three main changes: SDK compiler defaults, library extraction and linkage, and Windows esptool handling.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @pyproject.toml:
- Line 3: Update uv.lock to reflect the fbuild version 2.5.41 declared in
pyproject.toml, ensuring the editable package metadata is synchronized and uv
lock --check passes.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository: FastLED/fbuild/.coderabbit.yaml
• Review profile: CHILL
• Plan: Advanced
• Run ID: 9c33752e-1dd7-42e0-b571-a0caf26771c1

📥 Commits

Reviewing files that changed from the base of the PR and between 4c34c0f and f27d10d.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (13)

• .github/workflows/check-ubuntu.yml
• .github/workflows/check-windows.yml
• Cargo.toml
• ci/test_fractional_workflows.py
• crates/fbuild-build-arm/src/rp2040/orchestrator.rs
• crates/fbuild-build-arm/src/teensy/orchestrator.rs
• crates/fbuild-build-arm/src/teensy/teensy_linker.rs
• crates/fbuild-build-engine/src/pipeline/mod.rs
• crates/fbuild-build-engine/src/pipeline/sequential.rs
• crates/fbuild-library/src/library/esptool.rs
• crates/fbuild-library/src/library/esptool_tests.rs
• local-gate.toml
• pyproject.toml

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