fix(prism): ban non-causal TokenMix label-leak class

[echobt]

Summary

• Catch MLP-Mixer / TokenMix dense sequence mixers without a causal mask before pod rent (static NonCausalLabelLeak screen + agentic cheat code).
• Treat absurdly low recipe-v1 BPB (< 1.0) as the same label-leak class in sim/agentic.
• Document the causal LM ban for miners (docs/PRISM.md, recipe, external-miner).

Triggered by prod exploit b99a7047 (bpb≈0.23, score ~813k in ~12m) — already operator-revoked to Score(0)/rejected.

Test plan

• cargo test -p challenge-ast --lib source_cheats
• cargo test -p challenge-agentic sim_prism_tokenmix
• cargo test -p challenge-agentic sim_absurd_low_bpb
• CI green
• Deploy prism-challenge; confirm next TokenMix-class submit rejects pre-pod

Summary by CodeRabbit

• New Features

  • Added detection for non-causal sequence mixing that can expose future labels during next-token prediction.
  • Added the non_causal_label_leak result across cheat classifications and verdict reporting.
  • Added checks for unusually low BPB scores and expanded static source screening.

• Documentation

  • Clarified causal language-model requirements, prohibited patterns, failure outcomes, and permitted causal alternatives.
  • Updated Prism rules and prompt guidance to distinguish valid causal components from label leakage.

• Tests

  • Added coverage for TokenMix and MixerBlock detection while confirming causal Transformer patterns remain valid.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 75eb5067-b822-42dd-b2f3-a03764c9fc44

📥 Commits

Reviewing files that changed from the base of the PR and between b09d33e and 0d1806c.

📒 Files selected for processing (11)

• crates/challenge-agentic/src/lib.rs
• crates/challenge-agentic/src/prompts.rs
• crates/challenge-agentic/src/sim.rs
• crates/challenge-agentic/src/tools.rs
• crates/challenge-agentic/src/types.rs
• crates/challenge-ast/src/lib.rs
• crates/challenge-ast/src/source_cheats.rs
• crates/prism-challenge/src/orchestrator.rs
• docs/PRISM.md
• docs/PRISM_RECIPE.md
• docs/external-miner/prism.md

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📝 Walkthrough

Walkthrough

The PR adds AST detection for non-causal sequence mixing, integrates the finding into agentic simulator verdicts, classifies sub-1.0 BPB results, updates prompt rules, and documents the causal next-token contract.

Changes

Non-causal label-leak detection

Layer / File(s)	Summary
AST source detector crates/challenge-ast/src/source_cheats.rs, crates/challenge-ast/src/lib.rs	The AST crate detects unmasked sequence mixing, exposes the detector, integrates it into static source checks, and tests TokenMix, MixerBlock, and causal Transformer patterns.
Simulator verdict integration crates/challenge-agentic/src/types.rs, crates/challenge-agentic/src/tools.rs, crates/challenge-agentic/src/lib.rs, crates/challenge-agentic/src/sim.rs	The simulator maps static-source findings and BPB values below 1.0 to NonCausalLabelLeak. The agentic crate exposes the detector and parses the new cheat-code strings.
Prism rules and contracts crates/challenge-agentic/src/prompts.rs, crates/prism-challenge/src/orchestrator.rs, docs/PRISM.md, docs/PRISM_RECIPE.md, docs/external-miner/prism.md	Prompt versioning, orchestration documentation, and Prism contracts define non-causal label leakage and permitted causal mechanisms.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Submission
  participant static_source_cheat
  participant Simulator
  participant CheatCode
  Submission->>static_source_cheat: provide architecture and training sources
  static_source_cheat-->>Simulator: return source-cheat finding
  Simulator->>CheatCode: map non-causal finding to NonCausalLabelLeak
  Submission->>Simulator: provide evaluation metrics
  Simulator->>CheatCode: classify BPB below 1.0 as NonCausalLabelLeak

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Possibly related PRs

• BaseIntelligence/base#85: Both PRs modify Prism static source-cheat detection in the agentic simulator.
• BaseIntelligence/base#91: Both PRs update agentic Prism anti-cheat rules and prompt versioning.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/prism-noncausal-label-leak

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