test(coding-agent): align onboarding red-team with discovery error contract

[Yeachan-Heo]

Problem

Dev CI at 4f6e860 fails only on provider-onboarding-wizard-redteam with a stale expected string after #3927:

• Expected (stale): At least one model id is required
• Actual / intended public contract: At least one model id or model discovery is required.

Production (provider-onboarding.ts:249) correctly allows empty model lists when discovery is configured.

Fix

One-line test update in packages/coding-agent/test/provider-onboarding-wizard-redteam.test.ts to match the exact intended public error substring.

Non-goals

• No runtime behavior change
• No unrelated ACP/session work

Verification

bun test packages/coding-agent/test/provider-onboarding-wizard-redteam.test.ts
# 7 pass / 0 fail

[Yeachan-Heo]

Red-team review — MERGE_READY / CLEAR

Exact head: 23849a8503e24b334c90c92245ab17e275a6e67e
Base: dev @ 4f6e860d7
CI: Dev CI run 31127515306 — success (23 success / 5 skipped / 0 failure)

Scope

Surface	Result
Files	1 only — packages/coding-agent/test/provider-onboarding-wizard-redteam.test.ts
Production / runtime	None
Change	One assertion: stale "At least one model id is required" → intended public substring "At least one model id or model discovery is required"

Contract

Matches production provider-onboarding.ts:249:
throw new Error("At least one model id or model discovery is required.");

Empty model list after whitespace/comma parsing still rejects when discovery is absent; the public message correctly names discovery as the alternate path. Test uses established toThrow substring style (same as sibling "Provider id is required").

Regression risk

Risk	Verdict
Runtime behavior change	No
Weakens validation	No — still asserts rejection for empty models
Unrelated ACP/session	No

Local verification

bun test packages/coding-agent/test/provider-onboarding-wizard-redteam.test.ts → 7 pass / 0 fail (reproduced stale failure first on 4f6e860).

Verdict

MERGE_READY / CLEAR. Remaining #3927 provider baseline test-oracle fix.

— census red-team @ emergency audit batch