summary_additions/deletions/files always 0, summarize() never writes real values back

Description

The session code change metrics are always 0 in the DB, even when files are written/edited.

In packages/opencode/src/session/summary.ts, summarize() writes {additions: 0, deletions: 0, files: 0} to the session immediately, then computes diffs and stores them on the user message via updateMessage() — but never calls setSummary() again with the aggregated values.

For reference, revert.ts does it right:

summary: {
additions: diffs.reduce((sum, x) => sum + x.additions, 0),
deletions: diffs.reduce((sum, x) => sum + x.deletions, 0),
files: diffs.length,
}

Also, computeDiff() returns [] for non-git projects since Snapshot.track() returns undefined when vcs !== "git". It would be great if code changes worked without git — e.g. by diffing the write/edit tool call args directly.

VS Code, Windows 11.

Plugins

No response

OpenCode version

OpenCode v1.18.16

Steps to reproduce

1. Open OpenCode in a non-git directory
2. Ask it to create a file (e.g. "write a test file with 10 lines")
3. Run: sqlite3 ~/.local/share/opencode/opencode.db "SELECT summary_additions, summary_deletions, summary_files FROM session ORDER BY time_created DESC LIMIT 1"
4. Result: 0|0|0 despite a file being written

Screenshot and/or share link

No response

Operating System

Windows 11

Terminal

Windows Terminal