feat(models): prompt for reasoning level on DEFAULT assignments for all providers

[jason931225]

Problem

The model selector's reasoning menu only opened for the DEFAULT target when the model's provider was openai/openai-codex (requiresExplicitThinkingChoice in model-selector.ts). Picking an Anthropic reasoning model (e.g. claude-fable-5) for DEFAULT committed immediately with a bare selector:

• No way to pin an explicit effort for DEFAULT from the picker — the assignment silently inherited defaultThinkingLevel and rendered as (inherit).
• Worse, re-picking the same model stripped a hand-configured :xhigh suffix from modelRoles.default, so a carefully set default effort silently reverted.

Role-agent targets (executor/architect/planner/critic) already prompt for every reasoning model; DEFAULT was the odd one out.

Change

requiresExplicitThinkingChoice now returns true for the DEFAULT target whenever the model is reasoning-capable, regardless of provider. Everything downstream already works unchanged:

• the selector-controller composes the :level suffix into modelRoles.default and applies session.setThinkingLevel for default assignments,
• session startup honors an explicit suffix on the remembered default (explicitThinkingLevel), so the pinned effort survives restarts.

Non-reasoning models and temporary (role-less) model switches keep their current no-prompt behavior.

Tests

• model-selector-role-badge-thinking.test.ts:
  • new: DEFAULT assignment of an Anthropic reasoning model opens "Reasoning for Default", picking xhigh emits thinkingLevel: xhigh
  • new: non-reasoning Anthropic model still assigns directly without a prompt
  • updated: canonical-actions test now walks through the reasoning menu (seeded from the existing DEFAULT (low) badge) instead of expecting an instant commit
• model-selector-batch-thinking.test.ts: comment updated — Anthropic reasoning models now require an explicit choice on DEFAULT too

bun test on the touched suites: 108 pass / 0 fail (role-badge-thinking, batch-thinking, action-menu-role-binding, controller-batch, profiles, profiles-redteam, agent-session-role-thinking, role-thinking-helper-propagation, status-line-thinking). Biome and tsc --noEmit clean on touched files.

[Yeachan-Heo]

Superseded by dev-targeted PR #4390, which preserves @jason931225 credit and cherry-picks contributor commit 97bd828475095da585754622d4f2561f5c6ecc88 onto current dev. Exact head f8953e4563f382c8bd169bcfd175c43ec185f486 passed exact-head CI and independent review, then merged as 30628db609a99f3ae1f49cef6a10d2916e73ddf1. Closing this draft because it incorrectly targets main.