feat(deploy): per-board deploy method validation + fail-fast (#692)

[zackees]

#692. Pre-deploy guard against picking an unsupported upload_protocol — today's failure mode is a 30-180 s backend timeout that doesn't say 'this board doesn't do OTA'. Now it fails fast with a structured error naming the supported alternatives.

What ships

• FbuildError::UnsupportedDeployMethod { board, requested, supported } — structured fields
• validate_deploy_method(board, requested, &supported) — case-insensitive match, trim/lowercase on both sides, empty supported is a config-bug surface
• default_deploy_method(&supported) — first entry, matches PlatformIO's upload.protocol convention

Tests — 11 passed

Supported acceptance, unsupported rejection with structured fields, case-insensitive matching from board JSON, LPC845-BRK / ESP32 / Teensy / RP2040 worked examples, empty supported, default picker.

Out of scope (follow-up)

Wiring validate_deploy_method into each Deployer's pre-deploy hook + board JSON lookup — needs the board JSON parser to expose upload.protocols on the relevant struct.

Closes#692.

Summary by CodeRabbit

Release Notes

• Improvements
  • Enhanced validation of deployment methods with clearer error reporting that indicates which upload protocols are supported for your board.

[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: 4405253c-0c06-4278-84ea-0b9a283924c3

📥 Commits

Reviewing files that changed from the base of the PR and between b480b22 and 638155d.

📒 Files selected for processing (3)

• crates/fbuild-core/src/lib.rs
• crates/fbuild-deploy/src/lib.rs
• crates/fbuild-deploy/src/method_validation.rs

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📝 Walkthrough

Walkthrough

Adds a new UnsupportedDeployMethod variant to FbuildError with board, requested, and supported fields. Introduces a method_validation module in fbuild-deploy exporting validate_deploy_method (case-insensitive matching with normalization) and default_deploy_method (returns first supported entry), plus unit tests.

Changes

Deploy Method Validation

Layer / File(s)	Summary
UnsupportedDeployMethod error variant crates/fbuild-core/src/lib.rs	Adds UnsupportedDeployMethod { board: String, requested: String, supported: String } to FbuildError with a formatted #[error(...)] message reporting all three fields.
validate_deploy_method and default_deploy_method crates/fbuild-deploy/src/lib.rs, crates/fbuild-deploy/src/method_validation.rs	Exports the new method_validation submodule; adds module docs and implements validate_deploy_method (trims/lowercases requested, rejects empty supported list, case-insensitive match, returns error with comma-separated alternatives on mismatch) and default_deploy_method (returns first supported entry or None).
Unit tests crates/fbuild-deploy/src/method_validation.rs	Covers acceptance, structured error field assertions, case-insensitive board JSON and requested method handling, empty-supported-list rejection with placeholder text, default method selection, and whitespace/uppercase normalization.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A rabbit hops in, checks the board's allowed list,
If your protocol's missing — you won't be missed!
esptool? cmsis-dap? Let's see what you've got,
Trim it, lowercase it, match or it's not.
Fail fast, friend! No more mysterious hang —
The error speaks clearly with a satisfying clang. 🎉

🚥 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 accurately summarizes the main change: introducing per-board deploy method validation with fail-fast behavior to address unsupported protocol selection.
Linked Issues check	✅ Passed	The PR implements all core requirements from issue #692: the new error type carries structured fields, validate_deploy_method performs case-insensitive matching with trimming, default_deploy_method returns first supported entry, and empty supported lists are treated as configuration bugs.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to the validation logic: new FbuildError variant, method_validation module with two public functions, and comprehensive tests. No unrelated changes present.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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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/692-deploy-method-validation

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