The headline

Every song forged on SongForgeAI now carries a per-line authorship ledger. Each line is tagged with one of four states:

ai-generated — produced by the war room, untouched since
human-edited — produced by the war room, then changed by the user
human-original — written entirely by the user (Refine mode lock, paste, manual entry)
refined — the user pasted lyrics and the gauntlet rewrote a line

The ledger is computed automatically. Every line edit on the dashboard updates it. Every refine pass recomputes it. Every human-original input pushes the human-authorship percentage up.

The ledger is downloadable as a signed JSON file via the attribution receipt on every song's detail page. The receipt names the song, the date, the per-line breakdown, the rubric version that scored it, the model id that generated it, and a deploy SHA proving the configuration. It is structured. It is auditable. It is what a copyright defense actually needs.

This is the single move on SongForgeAI that I would call category-defining. No other AI lyric tool ships it. The reason is not technical difficulty — it's that nobody else thought it through legally first.

Why this matters

The copyright problem

U.S. Copyright Office (March 2023): works produced by AI without sufficient human authorship are not eligible for copyright protection. The threshold is "sufficient human authorship" — undefined precisely, but clearly above "I typed a prompt." Below that threshold, anyone can copy your AI-generated lyrics and you have no legal recourse.

The practical outcome: a songwriter who wants to release a song that used an AI tool needs to be able to prove WHICH lines they themselves wrote. A label that wants to sign a song needs to vet that the human-authorship is real. A music publisher that wants to register a copyright needs to defend the registration if challenged. None of these flows have been served by AI lyric tools to date — the tools produce a wall of text and don't tell anyone what came from where.

The submission problem

Every major label, every sync-licensing house, every publishing administrator now requires an "AI disclosure" form on submitted material. The forms ask: was AI used, and if so, how much. Songwriters fill them out from memory and hope. The labels accept the disclosures and hope. The hope is not durable.

An attribution receipt converts the disclosure from memory + hope into a structured artifact. The submission attaches a signed JSON file. The label opens it. Everyone knows exactly what they're dealing with.

The trust problem

If you tell someone "I wrote this with AI help," they will assume the worst case unless you give them a structure for the better case. The ledger gives them the structure. "65% human-original, 20% human-edited, 15% AI-generated" is a different conversation than "I used AI." The first is a number you can argue with. The second is a vibe.

How the ledger is computed

Every line in a forged song starts tagged ai-generated. The forge engine doesn't have to know the ledger exists — the lines come out of Claude with no annotation, and the writeback assigns the initial tag.

From there, the ledger is mutated by every interaction:

1. Inline line edits on the dashboard

The dashboard's per-line editor compares each saved line against the prior version. If the line text changed and the prior tag was ai-generated, the new tag is human-edited. If the prior tag was already human-original or human-edited, it stays.

2. Section rewrites via the gauntlet

When the gauntlet refines a section, the affected lines get tagged refined. The refined tag preserves the human-original / human-edited tag of any line the gauntlet didn't touch — partial refinement keeps partial human authorship intact.

3. Refine mode (locked lines + preservation)

In Refine mode, the user pastes lyrics and locks the lines they wrote. Locked lines start human-original and stay that way through any number of refine passes. Unlocked lines that the editorial panel changes become refined (or stay human-original if the panel left them alone within the preservation budget).

4. Manual paste / direct typing

Lines pasted into Refine mode without going through a forge are human-original from the start. The user can also manually type lines into the line editor on the dashboard; those are human-original too.

What the receipt actually contains

The downloadable receipt is a signed JSON file. Schema:

{
  "songId": "abc123",
  "title": "Heartbreak Diner",
  "forgedAt": "2026-04-27T18:42:11Z",
  "rubricVersion": "1.0",
  "modelId": "claude-sonnet-4-20250514",
  "deployShA": "0309346e",
  "ledger": [
    { "line": 1, "text": "The diner closed at midnight", "tag": "ai-generated" },
    { "line": 2, "text": "but the lights still hum", "tag": "human-edited" },
    { "line": 3, "text": "the waitress wipes down booth four", "tag": "human-original" },
    ...
  ],
  "summary": {
    "totalLines": 32,
    "aiGenerated": 12,
    "humanEdited": 7,
    "humanOriginal": 11,
    "refined": 2,
    "humanAuthorshipPct": 56
  },
  "signature": "sha256:..."
}

The signature is computed over the canonical-form JSON minus the signature itself, using a server-side secret. A challenger can recompute the signature, but cannot fabricate a valid one. The signature proves the receipt was generated by SongForgeAI's pipeline at the deploy SHA cited.

The receipt is auditable: a copyright lawyer or label A&R can verify the math (sum of category counts equals totalLines, percentages match), inspect the per-line tags, see the rubric version + model id used. Nothing is hidden.

Where this lives in the product

Every song detail page (dashboard + the public share at /s/[slug]) renders a contribution chip showing the human-authorship percentage. Public visitors see it too — the chip is a trust signal, not a private dashboard widget.

Every song's detail page has a "Download attribution receipt" link. Clicking it produces the signed JSON above as a .json file the user can save, forward, or attach to a submission.

The forge result page (V2's new design, B1538) surfaces the receipt link prominently in the trust-signals section below the lyrics. This was a deliberate placement decision in the design council (B1537) — panelist #50 (the music-industry executive) flagged it: "I see no contribution ledger, no attribution receipt, no quality signal. Why would a label trust this?" The receipt link is the answer to that question, and it's now visible on every result.

What this is NOT

Not a copyright registration. The receipt is evidence; it doesn't replace filing with the U.S. Copyright Office or the equivalent in your jurisdiction. It supports the registration's defensibility.

Not a guarantee. Copyright law is complicated and jurisdiction-specific. The receipt gives you the artifact courts and labels actually need. It does not guarantee the outcome of any specific dispute.

Not retroactive (yet). Songs forged before the contribution ledger landed (B1481+ for the ledger, B1518 for the signed receipt) carry NULL ledgers. They render with a "no ledger available — this song predates the system" notice instead of the chip. Future builds may backfill what's inferable from the version history.

Not a "watermark." The receipt is metadata about the song, not embedded into the lyric text. It travels with the song record, not the words. A user who copies the lyric text into another tool loses the receipt — and the protection it represents.

The principle

Every other AI generation product has a quiet hostility to authorship questions. The output is presented as if it has none — as if asking "who wrote this?" is impolite. The result is that real songwriters (the ones with skin in the copyright game) treat the tools with appropriate suspicion, and the tools never get used for the work that matters.

The contribution ledger flips this. SongForgeAI takes the question seriously. Every line is tagged. Every receipt is signed. The platform answers the authorship question before anyone asks.

That's the pitch to the music industry: this tool produces work you can defend. Use it, edit it, refine it — the ledger tracks every change. When you submit your song to a label, you submit the receipt with it. When you register the copyright, you have the per-line evidence. When someone challenges the registration, the signed JSON proves what was human and what wasn't.

Most lyric tools want you to forget AI was involved. SongForgeAI builds the artifact you need precisely because it was.

The ask

If you write songs you intend to release, every song you forge on SongForgeAI now carries the receipt as standard. Try a forge. Open the result. Click "View attribution receipt." Save the JSON. That's the artifact your future copyright registration leans on.

For the music industry: the receipt schema is documented at /songwriting/contribution-log-methodology. Free to inspect. Free to challenge. Built to be defensible.

Per-line authorship for AI-assisted lyrics. Receipts that hold up.