This improves Rust prompt-building by deduplicating repeated CLAUDE instruction content, surfacing clearer project-context metadata, and truncating oversized instruction payloads so local rules stay useful without overwhelming the runtime prompt.
The change preserves ancestor-chain discovery while making the rendered context more stable, compact, and readable for downstream compaction and CLI flows.
Constraint: Keep existing CLAUDE.md discovery semantics while reducing prompt bloat
Constraint: Avoid adding a new parser or changing user-authored instruction file formats
Rejected: Introduce a structured CLAUDE schema now | too large a shift for this parity slice
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: If richer instruction precedence is added later, keep duplicate suppression conservative so distinct local rules are not silently lost
Tested: cargo fmt; cargo clippy --all-targets --all-features -- -D warnings; cargo test -q
Not-tested: Live end-to-end behavior with very large real-world CLAUDE.md trees
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