> ## Documentation Index
> Fetch the complete documentation index at: https://docs.memvid.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Time Index Track

> v2.1's timeline fast-path

The Time Index Track adds deterministic timestamps to the file:

* Defined in `memvid-core/src/io/time_index.rs`
* Uses `TIME_INDEX_MAGIC = MVTI` header followed by entry count and `(timestamp, frame_id)` tuples
* `Memvid::commit()` sorts buffered entries, writes them immediately before the TOC, calculates A BLAKE3 checksum, and updates `Toc.time_index`
* `Stats.has_time_index` surfaces to CLI and SDKs to show readiness

### Query behavior

1. CLI/SDK builds a `TimelineQuery` specifying `start_ts`, `end_ts`, and optional limit
2. Core memory-maps the track and binary-searches for the first entry ≥ `start_ts`
3. It iterates sequentially until `end_ts` or limit is reached, returning `TimelineEntry` structs referencing the canonical frames

If the track is absent, the kernel falls back to scanning frames inside the TOC, which is slower but preserves correctness.

### Repair commands

`memvid doctor --file demo.mv2 --rebuild-time-index` rebuilds the track from frame metadata, as mandated by the Golden Test Pack (CLI-009). The report lists action plans, severity, and status codes defined in `DoctorReport`/`DoctorActionDetail`.

> **Testing** - The crash harness and determinism suite must validate timeline queries after every recovery scenario to ensure the track was correctly replayed from the WAL.