fm.freemix.stem

{
  "$type": "com.atproto.lexicon.schema",
  "defs": {
    "main": {
      "description": "A stem (isolated track component). Top-level leaf (FM-549 s38: pulled out from under release.* ; release.stem -> stem). May optionally reference a parent track and/or a parent stems-group.",
      "key": "tid",
      "record": {
        "properties": {
          "aiDeclaration": {
            "description": "Declaration of AI involvement in creation",
            "properties": {
              "category": {
                "description": "Level of AI involvement",
                "knownValues": [
                  "none",
                  "assisted",
                  "augmented",
                  "generated"
                ],
                "maxLength": 100,
                "type": "string"
              },
              "description": {
                "description": "Creator's description of how AI was used",
                "maxLength": 1000,
                "type": "string"
              },
              "tools": {
                "description": "AI tools used",
                "items": {
                  "maxLength": 100,
                  "type": "string"
                },
                "maxLength": 10,
                "type": "array"
              }
            },
            "required": [
              "category"
            ],
            "type": "object"
          },
          "audioDurationMs": {
            "description": "Duration of the stem in milliseconds",
            "type": "integer"
          },
          "audioFormat": {
            "description": "Audio file format",
            "knownValues": [
              "wav",
              "flac",
              "mp3"
            ],
            "maxLength": 100,
            "type": "string"
          },
          "audioHash": {
            "description": "SHA-256 hash of the stem audio content",
            "maxLength": 200,
            "type": "string"
          },
          "audioSizeBytes": {
            "description": "Size of the audio file in bytes",
            "type": "integer"
          },
          "audioUrl": {
            "description": "DEPRECATED (FM-508): no longer emitted. Stem audio is private (gated download / app-served preview) and is never surfaced in the portable record. Field kept (optional) to tolerate pre-FM-508 records without a putRecord rewrite. Stems never get a public clip.",
            "format": "uri",
            "maxLength": 3000,
            "type": "string"
          },
          "bpmCentis": {
            "description": "Centi-BPM (BPM × 100), integer — the Lexicon model has no float type; decode as `bpmCentis / 100` on read. Mirrors `fm.freemix.release.track`.",
            "maximum": 99900,
            "minimum": 2000,
            "type": "integer"
          },
          "coverArtUrl": {
            "description": "URL to cover art image",
            "format": "uri",
            "maxLength": 3000,
            "type": "string"
          },
          "createdAt": {
            "description": "Record creation timestamp",
            "format": "datetime",
            "maxLength": 100,
            "type": "string"
          },
          "description": {
            "description": "Stem description",
            "maxLength": 5000,
            "type": "string"
          },
          "detachedAt": {
            "description": "FM-504 tombstone: when the parent link was severed",
            "format": "datetime",
            "maxLength": 100,
            "type": "string"
          },
          "genres": {
            "description": "Genre classifications. Deliberately plural `genres` (it IS an array), NOT the track lexicon's singular `genre` — singular-for-an-array is misleading. Intentional divergence.",
            "items": {
              "maxLength": 50,
              "type": "string"
            },
            "maxLength": 10,
            "type": "array"
          },
          "label": {
            "description": "Human-readable name (e.g., 'Main Vocal', 'Acid Line', '808 Kit')",
            "maxLength": 100,
            "type": "string"
          },
          "license": {
            "description": "AT URI of the license grant record. For child stems this is the parent track's license, copied down at creation (FM-504)",
            "format": "at-uri",
            "maxLength": 3000,
            "type": "string"
          },
          "musicalKey": {
            "description": "Musical key (e.g., 'Am', 'F#m', 'Bb'). Deliberately named `musicalKey`, NOT the track lexicon's `key`: `key` is dangerously overloaded in a data layer (record keys, rkeys, map keys), so `musicalKey` is collision-proof and self-documenting. Intentional divergence.",
            "maxLength": 10,
            "type": "string"
          },
          "notes": {
            "description": "Generic freeform notes for this stem (FM-550, s41). Any purpose — processing notes, licensing caveats, or an ad-hoc credit like 'Drummer: Joey Beats'. Deliberately NOT the structured #trackCredits block: most credit roles are meaningless on a stem, so a freeform escape hatch covers the rare case. Stems carry no structured credits.",
            "maxLength": 1000,
            "type": "string"
          },
          "parentGroup": {
            "description": "AT URI of the parent fm.freemix.group.stems this stem belongs to (optional). FM-549 s38: stems may carry an optional parentTrack AND an optional parentGroup back-ref — the only upward refs in the model (containers otherwise point down at members).",
            "format": "at-uri",
            "maxLength": 3000,
            "type": "string"
          },
          "parentGroupCid": {
            "description": "CID of the parent stems-group record (pins to exact version).",
            "format": "cid",
            "maxLength": 200,
            "type": "string"
          },
          "parentTrack": {
            "description": "AT URI of the parent track this stem belongs to (optional for standalone stems)",
            "format": "at-uri",
            "maxLength": 3000,
            "type": "string"
          },
          "parentTrackCid": {
            "description": "CID of the parent track record (pins to exact version)",
            "format": "cid",
            "maxLength": 200,
            "type": "string"
          },
          "position": {
            "description": "Display order position (0-indexed)",
            "minimum": 0,
            "type": "integer"
          },
          "previouslyAttachedToCid": {
            "description": "FM-504 tombstone: CID of the former parent track record at detach time",
            "format": "cid",
            "maxLength": 200,
            "type": "string"
          },
          "previouslyAttachedToUri": {
            "description": "FM-504 tombstone: AT URI of the former parent track, set when this stem was detached (parent deleted, keep-stems path). Preserves remix-tree placement + royalty-lineage reconstructability",
            "format": "at-uri",
            "maxLength": 3000,
            "type": "string"
          },
          "stemType": {
            "description": "Type/category of the stem",
            "knownValues": [
              "drums",
              "bass",
              "vocals",
              "synth",
              "guitar",
              "keys",
              "pad",
              "lead",
              "fx",
              "other",
              "808",
              "synth-strings",
              "vocal-sample",
              "space-echo",
              "plate",
              "african-percussion",
              "surdo",
              "kete"
            ],
            "maxLength": 100,
            "type": "string"
          },
          "tags": {
            "description": "Freeform tags",
            "items": {
              "maxLength": 50,
              "type": "string"
            },
            "maxLength": 10,
            "type": "array"
          },
          "title": {
            "description": "Stem title (first-class stems). `label` remains the required human-readable name; `title` is the unified-on-title field added in FM-504",
            "maxLength": 300,
            "type": "string"
          }
        },
        "required": [
          "stemType",
          "label",
          "audioHash",
          "audioDurationMs",
          "audioFormat",
          "audioSizeBytes",
          "createdAt"
        ],
        "type": "object"
      },
      "type": "record"
    }
  },
  "id": "fm.freemix.stem",
  "lexicon": 1
}