fix(statemachine): re-initialise StateMachineScript on restart

[chsami]

Problem

Found by the release E2E harness (#1933) script-lifecycle check, which starts and stops a built-in script twice.

Plugins inject their script as a singleton, so the same StateMachineScript instance is reused across plugin stop/start. Stopping removed the registry entry but left initialized = true, so on the next start step() skipped initialize():

• the script never re-registered, so getRegistry() (and GET /statemachine) no longer listed it
• it resumed from the state it was in when stopped, with stale loop/transition counters, trace and snapshot

Fix

• Stopping clears initialized and the published snapshot, so the next step() re-runs initialize() (re-registers and starts from initialState()).
• initialize() resets previous state, last transition, counters and the trace buffer.
• Unregistering uses REGISTRY.remove(name, this) so a stale instance stopping cannot drop a newer instance's entry.
• Stop cancels the loop first, then resets under a short lifecycle lock shared with initialize() and snapshot publication; an interrupted (cancelled) in-flight step cannot re-register or republish a stale snapshot. Nothing blocks waiting for a running step.

Tests

StateMachineScriptRestartTest covers start -> stop -> start: registry membership after each step, initial state, reset counters/trace, and stale-instance unregister. Both tests fail on development and pass with this change. Further tests cover a cancelled step after stop and a stop during the state action. ClientThreadGuardrailTest baseline unchanged (987).

Live

Release E2E harness (#1933) script-lifecycle check, merged locally on top of this branch (not part of this PR), F2P account on world 383: PASS, registry [registered, registered], state at start [SCAN_NPCS, SCAN_NPCS] across both start/stop cycles, script pool back to core size after each stop.

🤖 Generated with Claude Code

https://claude.ai/code/session_01LjtEMzQHGuq4M1Mpqk9pPV

[coderabbitai]

Walkthrough

StateMachineScript now declares initialized as volatile. Initialization resets previous-state and transition metadata, counters, and the trace buffer. Shutdown clears initialized and the published snapshot, and removes the registry entry only when it maps to the stopping instance. Added tests cover restarting a stopped script and stopping an instance without unregistering its same-name replacement.

Priority: ➖ Normal

Merge Risk: 🟡 Moderate · up to cc980

A script stopping during a scheduled step can remain registered or expose stale state. Coordinate stepping with shutdown before merging.

Pre-merge checks | 4 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 2 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.
Title check		The title clearly and concisely describes the main change: re-initializing StateMachineScript when it restarts.
Description check		The description directly explains the restart lifecycle issue, the implementation changes, and the related tests.

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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
@runelite-client/src/main/java/net/runelite/client/plugins/microbot/statemachine/StateMachineScript.java:
- Line 296: Serialize lifecycle operations in StateMachineScript so step()
cannot reinitialize or publish a snapshot concurrently with shutdown(). Use a
shared lifecycle guard for step() and shutdown(), or wait for any running step()
to finish before shutdown clears initialized, the registry entry, and snapshot;
ensure the script cannot be re-registered during shutdown.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository UI
• Review profile: CHILL
• Plan: Advanced
• Run ID: a3cda866-dcaa-4338-ad58-7bc78103e5d2

📥 Commits

Reviewing files that changed from the base of the PR and between e5863ae and cc98074.

📒 Files selected for processing (2)

• runelite-client/src/main/java/net/runelite/client/plugins/microbot/statemachine/StateMachineScript.java
• runelite-client/src/test/java/net/runelite/client/plugins/microbot/statemachine/StateMachineScriptRestartTest.java

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