Add prompt_style A/B experiment to daily-file-diet with concise/detailed prompt branching

[Copilot]

This updates daily-file-diet to run a prompt_style experiment so we can compare the existing dense prompt against a lean variant without changing the workflow’s core behavior. The goal is to measure whether the concise prompt preserves issue quality while reducing token/runtime cost.

• Experiment configuration (frontmatter)

  • Added experiments.prompt_style using object form with:
    • variants: [detailed, concise]
    • primary metric: issue_completeness_score
    • secondary metrics: effective_token_count, run_duration_ms
    • guardrails for issue creation success and empty output
    • min_samples, weight, start_date, and tracking issue metadata

• Prompt variant routing

  • Wrapped prompt body in a prompt_style conditional.
  • detailed path keeps the existing full protocol as baseline.
  • concise path uses a compressed instruction set that still requires:
    • largest Go file detection
    • 800-line threshold behavior
    • Serena semantic analysis
    • issue output with split proposals, test plan, and acceptance checklist

• Compiled workflow artifact update

  • Regenerated daily-file-diet.lock.yml to include experiment activation/assignment plumbing and prompt interpolation for the selected variant.

{{#if experiments.prompt_style == 'concise'}}
Find the largest `.go` source file... If it has **800+ lines**, open a GitHub issue titled
`[file-diet] Refactor <filename> (<N> lines)` with findings, 2–4 split proposals,
a test coverage plan, and an acceptance checklist. Use `serena` for semantic analysis.
{{#else}}
[existing detailed prompt]
{{/if}}

[pelikhan]

@copilot merge main and recompile

[Copilot]

Pull request overview

Adds a prompt_style A/B experiment (detailed vs. concise) to daily-file-diet so the existing verbose refactoring prompt can be compared against a compressed variant on issue quality and token/runtime cost, and regenerates the corresponding lock file plus several other lock files affected by an unrelated checkout-prompt format change.

Changes:

• Add object-form experiments.prompt_style frontmatter (variants, hypothesis, primary/secondary/guardrail metrics, weight, start date, tracking issue) to daily-file-diet.md.
• Wrap the prompt body in {{#if experiments.prompt_style == 'concise'}} … {{#else}} … {{/if}} with a one-paragraph concise variant and the original detailed prompt as fallback.
• Regenerate daily-file-diet.lock.yml with experiment plumbing (restore/pick/upload steps, artifact, push_experiments_state job, prompt env injection) and pick up unrelated checkout-prompt text reformatting in seven other lock files.

Show a summary per file

File	Description
.github/workflows/daily-file-diet.md	Adds prompt_style experiment frontmatter and conditional prompt branching.
.github/workflows/daily-file-diet.lock.yml	Regenerated lock file adding experiment selection, artifact, and push job.
.github/workflows/smoke-update-cross-repo-pr.lock.yml	Regenerated checkout-prompt line formatting only.
.github/workflows/smoke-create-cross-repo-pr.lock.yml	Regenerated checkout-prompt line formatting only.
.github/workflows/smoke-codex.lock.yml	Checkout-prompt formatting plus heredoc marker rehash.
.github/workflows/smoke-claude.lock.yml	Regenerated checkout-prompt line formatting only.
.github/workflows/schema-feature-coverage.lock.yml	Checkout-prompt formatting plus heredoc marker rehash.
.github/workflows/schema-consistency-checker.lock.yml	Regenerated checkout-prompt line formatting only.
.github/workflows/pr-sous-chef.lock.yml	Regenerated checkout-prompt line formatting only.
.github/workflows/glossary-maintainer.lock.yml	Regenerated checkout-prompt line formatting only.

Copilot's findings

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• Files reviewed: 10/10 changed files
• Comments generated: 1