opencode run and HTTP POST /session/{id}/message fail with NOT NULL constraint failed: session_message.seq (1.15.13) #31413

Description

Starting with OpenCode 1.15.13, every code path that creates a new session message fails immediately with a SQLite NOT NULL constraint violation on session_message.seq. The session is created and listed correctly, but the first message (and every subsequent one) cannot be inserted.

This blocks opencode run and the HTTP POST /session/{id}/message route. The failure is in the new-row insert path of appendMessage (called from session.next.agent.switched in the bundled SessionPrompt code). Existing sessions stored in the local DB continue to work; new sessions are unusable for any new message.

Plugins

None.

OpenCode version

1.15.13 (Homebrew, darwin/arm64)

Steps to reproduce

1. opencode run (any prompt)

$ opencode run --model opencode-go/minimax-m3 --dir "$PWD" \
    --title warmup --dangerously-skip-permissions "echo hello"
Error: {
  "name": "UnknownError",
  "data": {
    "message": "Unexpected server error. Check server logs for details.",
    "ref": "err_c822fa6f"
  }
}

2. HTTP POST /session/{id}/message

$ opencode serve --port 4096 --hostname 127.0.0.1 &
$ curl -sS -X POST http://127.0.0.1:4096/session -H 'Content-Type: application/json' -d '{}'
{"id":"ses_1576d5db9ffeakrbrmYGMdq6dJ","slug":"glowing-panda", ...}

$ curl -sS -X POST http://127.0.0.1:4096/session/ses_1576d5db9ffeakrbrmYGMdq6dJ/message \
    -H 'Content-Type: application/json' \
    -d '{"model":{"providerID":"opencode-go","modelID":"minimax-m3"},
         "parts":[{"type":"text","text":"Reply with just the word ok"}]}'
{"name":"UnknownError","data":{"message":"Unexpected server error. ...","ref":"err_37d9088b"}}

Both opencode-go/minimax-m3 and minimax-coding-plan/MiniMax-M3 fail identically, so the bug is in OpenCode itself, not the provider.

3. Error from server log

ERROR service=server ref=err_37d9088b
  error=NOT NULL constraint failed: session_message.seq
  cause=SQLiteError: NOT NULL constraint failed: session_message.seq
    at run (unknown)
    at #run (bun:sqlite:185:20)
    at appendMessage (/$bunfs/root/chunk-9re0szbd.js:2:62522)
    at session.next.agent.switched (/$bunfs/root/chunk-9re0szbd.js:2:56643)
    at pC (/$bunfs/root/chunk-9re0szbd.js:2:56588)
    at tn (/$bunfs/root/chunk-9re0szbd.js:2:62564)
    at <anonymous> (/$bunfs/root/chunk-9re0szbd.js:2:62753)
    at SessionPrompt.createUserMessage
    at SessionPrompt.prompt
    at SessionHttpApi.prompt
  failed

4. Local DB schema (intact)

CREATE TABLE `session_message` (
  `id` text PRIMARY KEY,
  `session_id` text NOT NULL,
  `type` text NOT NULL,
  `time_created` integer NOT NULL,
  `time_updated` integer NOT NULL,
  `data` text NOT NULL,
  `seq` integer NOT NULL,
  ...
);
CREATE UNIQUE INDEX `session_message_session_seq_idx`
  ON `session_message` (`session_id`, `seq`);

seq has no DEFAULT. Existing rows all have a non-null seq, so the schema is intact. The bug is in appendMessage not providing a value for seq on the new-row insert.

Screenshot and/or share link

N/A — headless run, no UI. Server log lines included above.

Operating System

macOS 26 (darwin/arm64)

Terminal

iTerm2 (headless invocation; not relevant)

Suggested fix area

appendMessage in packages/opencode (bundled into chunk-9re0szbd.js). It should compute the next seq for the session (MAX(seq)+1 for the session, or 1 if it has no messages yet) before the INSERT, or the schema should give seq a DEFAULT.