The runtime now discovers both legacy and current Claude config files at
user and project scope, merges them in precedence order, and carries the
resolved model, permission mode, instruction files, and MCP server
configuration into session startup.
This keeps CLI defaults aligned with project policy and exposes configured
MCP tools without requiring manual flags.
Constraint: Must support both legacy .claude.json and current .claude/settings.json layouts
Constraint: Session startup must preserve CLI flag precedence over config defaults
Rejected: Read only project settings files | would ignore user-scoped defaults and MCP servers
Rejected: Delay MCP tool discovery until first tool call | model would not see configured MCP tools during planning
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep config precedence synchronized between prompt loading, session startup, and status reporting
Tested: cargo fmt --all --check; cargo clippy --workspace --all-targets --all-features -- -D warnings; cargo test --workspace --all-features
Not-tested: Live remote MCP servers and interactive REPL session startup against external services
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
