fix(machine-a-tron): invalidate stale boot actions

[jayzhudev]

A retrying Machine-a-Tron boot action can remain at the front of the action queue after a power change. This prevents the queued power-off cleanup and power-cycle timer from running. In the observed failure, a stale
InitialDiscoveryRequest kept retrying while the BIOS job remained scheduled until the test timed out.

This change invalidates work tied to the previous boot when the machine powers off or cycles. BMC-scoped setup, BMC DHCP, and existing power-off cleanup remain queued. Pending machine and agent deadlines are cleared.

Action classification uses an exhaustive match so future FsmAction, Timer, or BmcEvent variants require an explicit power-change policy.

Related issues

Resolves #4429

Type of Change

• Add - New feature or capability
• Change - Changes in existing functionality
• Fix - Bug fixes
• Remove - Removed features or deprecated functionality
• Internal - Internal changes (refactoring, tests, docs, etc.)

Breaking Changes

• This PR contains breaking changes

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• No testing required (docs, internal refactor, etc.)

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• crates/machine-a-tron/src/machine_state_machine.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• crates/machine-a-tron/src/machine_state_machine.rs

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Summary by CodeRabbit

• Bug Fixes
  • Improved machine power-change cleanup by removing outdated queued operations from the previous boot.
  • Preserved essential BMC setup, BMC DHCP, and power-off cleanup actions.
  • Ensured DHCP retry state resets appropriately when machine DHCP work is discarded.
• Tests
  • Added coverage for retaining required actions and abandoning obsolete operations.

Walkthrough

Power-change cleanup now removes stale machine-side actions from the queue while retaining BMC setup, BMC DHCP, and power-off cleanup actions. Machine DHCP retry state resets only when machine DHCP work is removed. Tests cover these rules.

Changes

Power-change cleanup

Layer / File(s)	Summary
Implement and wire power-change cleanup crates/machine-a-tron/src/machine_state_machine.rs	The cleanup helper removes stale machine work, preserves BMC and power-off actions, resets machine DHCP retry state when required, and handles power-cycle and power-off events.
Validate queued-action behavior crates/machine-a-tron/src/machine_state_machine.rs	Tests cover abandoned machine actions, retained BMC and power-off actions, unchanged state without machine work, and the replacement cleanup helper.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• NVIDIA/infra-controller#4343: Both PRs modify machine DHCP cleanup and retry-state reset during power transitions.
• NVIDIA/infra-controller#4389: This cleanup determines which queued machine-side boot actions survive power transitions.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: invalidating stale boot actions after a power change.
Description check	✅ Passed	The description accurately explains the stale-action bug, the fix, retained work, cleared deadlines, and test coverage.
Linked Issues check	✅ Passed	The changes satisfy issue #4429 by abandoning stale boot-scoped actions while preserving BMC-scoped work and power-transition actions.
Out of Scope Changes check	✅ Passed	The changes are limited to power-change action cleanup and related tests, which directly support issue #4429.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing Touches

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• Create PR with unit tests

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🧹 Nitpick comments (1)

crates/machine-a-tron/src/machine_state_machine.rs (1)

1626-1627: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Cover the power-change integration path.

This test calls the cleanup helper directly. It does not verify that fsm_event invokes the helper for both Event::PowerCycle and Event::PowerOff, or that the pending deadlines are cleared.

Add focused table cases through the power-change entry point and assert the queue, retry state, and deadlines.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/machine-a-tron/src/machine_state_machine.rs` around lines 1626 - 1627,
Add focused table-driven tests through the fsm_event power-change entry point
rather than calling abandon_machine_actions_on_power_change directly. Cover both
Event::PowerCycle and Event::PowerOff, asserting that actions are cleared, retry
state is updated, and pending deadlines are cleared.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@crates/machine-a-tron/src/machine_state_machine.rs`:
- Around line 1626-1627: Add focused table-driven tests through the fsm_event
power-change entry point rather than calling
abandon_machine_actions_on_power_change directly. Cover both Event::PowerCycle
and Event::PowerOff, asserting that actions are cleared, retry state is updated,
and pending deadlines are cleared.

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📥 Commits

Reviewing files that changed from the base of the PR and between 395a11f and 444e00b.

📒 Files selected for processing (1)

• crates/machine-a-tron/src/machine_state_machine.rs