RFC 0003: Incremental Parsing Strategy

Status

Accepted

Context

Proposal target includes incremental responsiveness (<100ms for files under 5k LOC).

Decision

Adopt a staged approach:

1. Correct baseline implementation first.
2. Incremental optimization with InputEdit and changed-range narrowing behind benchmark evidence.

Alternatives considered

1. Full incremental complexity from day one.
2. Full reparse forever.

Rationale

Correctness-first minimizes early defect risk; benchmark-driven optimization avoids premature complexity.

Consequences

• Early versions may reparse more broadly.
• Optimization milestones are explicitly measurable.

Incremental cache contract

• A file that cannot be read keeps its cached extraction and counts as unchanged.
• A retained file stays in the merged output with the same Arc handle.
• The stale sweep never treats an unreadable file as removed.
• A first-tick read failure has no entry to keep and claims no counter.
• Oversized files and language changes re-extract and never duplicate a reused handle.