ADR-0001: Index filenames only

Date: 2026-06-11 / Status: Accepted

Decision

The index holds only filename, size, modified time, and attributes. No content index, no property/tag index, no preview.

Speed and RAM come from the “index filenames only” tradeoff. The RAM gate is engine-only ≤110B/file (M2), which is orders of magnitude incompatible with a content index
A content index inflates RAM by orders of magnitude (can reach 8GB-class)
Filename-only indexing lands at ≈100B/file (the ≤110B RAM gate is the target derived from this)
Real-world search syntax usage centers on substring, ext:, path:, size:, dm:; content:/regex: are niche (docs/RESEARCH.md)

No search over file contents or meta-properties
Under the same scope freeze, FTP/HTTP/ETP servers, FAT/exFAT/network drives (MVP), ReFS (MVP), and cross-platform support are also out of scope

The core (filename-only index, content index excluded) is a permanent decision (canonical source: the “do-not list” in AGENTS.md)
Volume-level NTFS indexing is the only production ingest path. The former folder-walk exception was removed with ADR-0024 because it duplicated the engine lifecycle while losing whole-volume coverage and USN replay.