Scheduled Tasks always launch on Opus 5, ignoring model picker and settings.json

Summary

Scheduled Tasks in the Claude desktop app (Code tab) always launch on Opus 5, regardless of the app's model picker or ~/.claude/settings.json (model and env.ANTHROPIC_MODEL). There is no per-task model field in the scheduled-task create/update flow.

Evidence

• 67 scheduled-task sessions across 2026-09-08 to 2026-09-11 were checked by counting the model field on every assistant turn in their transcript files (~/.claude/projects/<project>/*.jsonl).
• 63 of 67 ran 100% on claude-opus-5 from first turn to last, even though ~/.claude/settings.json has specified "model": "claude-sonnet-5" and env.ANTHROPIC_MODEL: "claude-sonnet-5" since 2026-09-05.
• The terminal CLI honors the same settings file correctly: claude -p --output-format json "ok" reports modelUsage: ["claude-sonnet-5"].
• Switching the app's model picker (Code tab, "landing" default) from Opus 5 to Sonnet 5 only affected turns of scheduled-task sessions that happened to already be in flight at that exact moment — 4 sessions show a mid-session split between claude-opus-5 and claude-sonnet-5 turns, timed to when the picker was toggled. Every scheduled task launched afterward (new session start) still started on claude-opus-5, unchanged.

Expected behavior

Scheduled tasks should either (a) inherit the app's current default model / settings.json at launch time, or (b) expose a model field on create_scheduled_task / update_scheduled_task so each routine can pin its own model.

Impact

Cost: routines that don't need Opus-level reasoning (daily digests, log syncs, simple checks) are billed at Opus rates with no way to opt down, for every recurring run.