# Schema

This document defines the contracts for canonical filenames and
`metadata.csv`. Filenames are human-readable descriptions; `record_id` is the
persistent machine identity.

## Canonical Filename Format

`YYYY-MM-DD.HHMM.Tool.Medium.Support.Dimensions[.RecNN].ext`

Examples:

```text
2025-07-15.0448.FountainPen.Ink.Paper.9x12.mp4
2026-06-29.UnknownTime.FountainPen.Ink.Paper.30x40.Rec11.mp4
2026-06-29.UnknownTime.FountainPen.Ink.Paper.30x40.Rec12.mp4
```

### Filename fields

- `YYYY-MM-DD` — documented finish date.
- `HHMM` — documented finish time in 24-hour local civil time.
- `UnknownTime` — used when no reliable finish time is documented.
- `Tool` — drawing instrument, such as `Pencil`, `FountainPen`, `BallpointPen`,
  or `Brush`.
- `Medium` — applied material, such as `Graphite` or `Ink`.
- `Support` — drawing surface, such as `Paper`, `IllustrationBoard`, or
  `WatercolorPaper`.
- `Dimensions` — support dimensions in inches; order preserves support
  orientation, such as `9x12` or `12x9`.
- `RecNN` — optional recording-sequence identifier used when documented order
  must be preserved or otherwise identical filenames require distinction.
  Numbering begins with `Rec01` and may continue across finish dates.
- `ext` — file extension.

### Filename rules

- Fields are separated by periods.
- Style and aesthetic classifications are excluded.
- `TL` is excluded because time-lapse is implicit in the primary collection.
- `0000` is reserved for a documented midnight finish time.
- `RecNN` identifies recording order only. It does not by itself establish a
  separate drawing, session, or completion state, and it does not reset merely
  because the documented finish date changes.
- `UnknownTime` records uncertainty; it is not replaced by an inferred time.
- Paper-surface variants such as `HotPress` and `ColdPress` may remain encoded
  in filenames until a dedicated metadata field is added.
- Historical relationships must not be inferred from filename similarity
  alone.

Tool and medium tokens in a filename describe documented materials, but older
filenames do not always encode an unambiguous one-to-one pairing. Metadata must
therefore preserve tool and medium sets without manufacturing positional pairs.

## Canonical Metadata Contract

`metadata.csv` indexes the validated canonical subset of MP4 files stored
directly in `Standard_Time_Lapses/`. Direct placement alone does not make a file
canonical: every released canonical file must have exactly one metadata row,
complete required technical fields, and the necessary rights and provenance
clearance. The canonical index contains 363 validated records and covers every MP4
stored directly in `Standard_Time_Lapses/` at the pinned revision.

The canonical index does not make provenance, unresolved, pre-standard, or
legacy files canonical.

### Identity and collection fields

| Field | Type | Meaning |
| --- | --- | --- |
| `file_name` | string | Repository-relative canonical video path. |
| `record_id` | string | Persistent identity in the form `tla-` plus 16 lowercase hexadecimal characters. |
| `collection_tier` | enum | `standard` for this index. |
| `is_canonical` | boolean | `true` for every row in this index. |
| `acquisition_protocol_version` | string | Protocol identifier; currently `standard-2025-07-13`. |

The initial `record_id` values were generated from a namespaced SHA-256 of the
published repository path. Once assigned, the stored value is authoritative and
must be retained across filename corrections or tier changes. New tooling must
assign an ID only when a record does not already have one. When a genuinely new
record is promoted from a noncanonical holding, its ID is seeded from that
object's prior archival path; it must not inherit an ID already attached to a
different object at the corrected destination path.

### Pre-Standard collection contract

`Pre_Standard_Time_Lapses/metadata.csv` indexes the 128 direct MP4 files in that
folder. Each row uses `collection_tier = pre_standard`, `is_canonical = false`,
and a blank `acquisition_protocol_version`. Pre-Standard status records a
different acquisition/documentation era; it does not remove the requirements
for stable identity, exact content hash and size, or encoded-stream metadata.

Dates, times, tools, media, support, and historical provenance may remain blank
when the surviving evidence is insufficient. Those blanks are historical
uncertainty, not failed technical ingestion.

### Session and material fields

| Field | Type | Meaning |
| --- | --- | --- |
| `date` | `YYYY-MM-DD` | Documented finish date. |
| `time` | `HH:MM` or blank | Documented finish time; blank means unknown. |
| `tool` | semicolon list | Ordered unique set of documented tools. |
| `medium` | semicolon list | Ordered unique set of documented media. |
| `support` | string | Physical drawing surface. |
| `dimensions` | string | Support dimensions in inches, such as `9x12`. |

Multiple values use semicolons:

```text
tool = Pencil;FountainPen
medium = Graphite;Ink
```

`tool` and `medium` are independent observed-value lists. Equal lengths and
positional correspondence are **not guaranteed**. Repeated media are collapsed
to one value. A future paired representation should use a structured field and
must be based on documented evidence rather than token position.

### Encoded-video fields

| Field | Type | Meaning |
| --- | --- | --- |
| `duration_seconds` | float | Encoded playback duration. |
| `width_px` | integer | Stored encoded width. |
| `height_px` | integer | Stored encoded height. |
| `orientation` | enum | Stored pixel orientation derived from width and height. |
| `encoded_frame_rate` | float | Encoded playback frame rate as reported by the container; fractional values are allowed. |
| `video_codec` | string | Encoded video codec. |
| `pixel_format` | string | Encoded pixel format. |
| `container` | string | Media container. |
| `has_audio` | boolean | Whether the stored file contains an audio stream. |
| `hub_xet_hash` | string | Lowercase 64-character Xet file ID from the pinned Hub resolve response's `X-Xet-Hash` header. This is distinct from the LFS-compatible SHA-256. |
| `size_bytes` | integer | Stored file size in bytes. |

These fields describe the published encoded file. They do not establish the
original frame-capture interval, real drawing duration, speed-up factor, camera
calibration, capture orientation, rotation, crop, or transcode lineage.

Canonical status identifies the active representative of a Standard record; it
does not assert that the encoded file is an unaltered or full-duration capture
master. A shortened derivative may be canonical when it is the verified active
representative and its limitation is disclosed in `notes`.

`encoded_frame_rate` must not be interpreted as drawing-time sampling rate.

### Historical provenance fields

| Field | Type | Meaning |
| --- | --- | --- |
| `original_filename` | string or blank | Independently documented historical filename. |
| `provenance_status` | string or blank | Current relationship status. |
| `legacy_provenance_path` | string or blank | Verified historical repository path. |
| `legacy_related_references` | string or blank | Related candidates, aliases, or rejected references. |
| `evidence_method` | string or blank | Primary evidence used for the status. |
| `provenance_reference_duration_delta_seconds` | float or blank | Duration delta to a referenced historical file. |
| `notes` | string or blank | Human-readable evidence or qualification. |

Blank provenance values mean that the field is not documented or not
applicable in the current release. A blank must not be promoted to a verified
relationship.

Observed provenance statuses include:

- `legacy_match_verified`
- `legacy_aliases_verified`
- `legacy_duplicate_removed`
- `legacy_candidates_rejected`
- `direct_root_upload`

Observed evidence methods include:

- `blob_identity`
- `visual_continuity`
- `visual_comparison`
- `commit_history`
- `manual_confirmation`
- `blob_identity_and_physical_date`

New enumerated values must be documented here before use.

## Missing-Value Rules

- Blank means unknown, not documented, or not applicable according to the field
  description.
- Blank numeric values must remain blank; they are not zero.
- Blank booleans must remain blank; they are not `false`.
- Uncertain dates and times must not be reconstructed from unsupported clues.
- Pre-Standard descriptive/provenance metadata may be less complete, but every
  published record must carry a collection-tier distinction, stable ID, exact
  content identity, and complete core encoded-video metadata.

## Required Validation

Before publication, the validator must confirm:

- unique `record_id`, `file_name`, and nonblank `hub_xet_hash`
- canonical paths remain directly under `Standard_Time_Lapses/`
- one consistent semicolon convention for multi-value fields
- valid dates, times, and dimensions
- complete core encoded-video metadata for every active Standard and
  Pre-Standard row
- orientation agrees with stored width and height
- canonical metadata paths match the canonical Viewer records
- every active standard and pre-standard metadata path resolves to a published
  repository file
- repository media absent from an active index is reported explicitly rather
  than silently treated as released data
- material lacking the necessary ownership or provenance clearance is absent
  from both active indexes

Run:

```bash
python tools/validate_metadata.py metadata.csv
```

Rebuild the v0.2 index from its pinned 335-row source and audited additions:

```bash
python tools/repair_metadata.py source_metadata.csv metadata.csv \
  --additions tools/metadata_additions_v0.2.csv
```