refactor(libsy): separate task context from judge instructions

[nachiketb-nvidia]

Superseded by #900, which includes this input refactor and the judge configuration refactor. Review and merge #900 → #901.

What

Separate conversation selection from the LLM judge's trailing routing instruction. Both judge types can use the same task window and reasoning removal; LLM requests keep their existing messages and prompt.

Why

Decision requests need conversation data without an instruction to emit LLM routing JSON. This is the first part of SWITCH-1687.

How

Extract TaskInput::messages and have the existing ClassifierInput implementation append its LLM instruction afterward. Routing, thresholds, affinity, and fallback are unchanged.

Validation

• All 26 existing capability classifier tests passed before and after the refactor.
• cargo fmt --all --check and commit-hook workspace Clippy.
• No new test functions; no live provider calls.

Notes for reviewers

This change is included in #900. The active stack is #900 → #901.

One file, +10 / −2 lines.

Summary by CodeRabbit

• Refactor
  • Updated internal message selection for classification requests; no user-visible behavior changes are expected.

[github-actions]

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📥 Commits

Reviewing files that changed from the base of the PR and between 12922d5 and 80a16a7.

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• crates/libsy/src/algorithms/llm_class.rs

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Walkthrough

TaskInput now selects messages through an inherent messages method. ClassifierInput::build_messages delegates message selection to that method and retains the trailing instruction for windowed requests.

Changes

Message Selection

Layer / File(s)	Summary
Message selection and build delegation crates/libsy/src/algorithms/llm_class.rs	TaskInput::messages contains the existing selection and reasoning-removal logic. ClassifierInput::build_messages delegates selection to it and retains the conditional trailing instruction.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 80a16

The refactor is mergeable with no identified behavior or availability risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main refactor: separating shared task context from judge-specific instructions.

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_{A rabbit checks each message in a row
Then sends the chosen words along
A window adds its routing note
The helper keeps the old path clear
Hop, hop, the messages flow!}

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