feat(billing): honor the gateway's free-tier model marks — authed fetches, safe defaults, locked pickers

[adboio]

tl;dr

• pass auth token with all model list requests, so the gateway marks restricted models
• UI updates to show restricted models

testing

free tier - model picker locked
click a locked model

full vibe-description:

Problem

Model pickers can't see the gateway's free-tier gate (PostHog/posthog#70951): every /v1/models fetch is anonymous, so free-tier users see all models as available, and new sessions default to claude-opus-4-8 — which 403s a free-tier org's very first message.

Changes

Third slice of the cutover stack (stacked on #3487):

• Authed models fetches wherever a token exists — Claude adapter, workspace-server preview/models routes (new gatewayAuthToken() on the auth adapter), cloud agent, and the pi harness — so the gateway can mark restricted models (allowed: false). The models caches key on auth presence so authed/anonymous responses never cross-serve.
• Safe defaults: defaults are unchanged for everyone — pickAllowedModel only swaps when the gateway explicitly marked the preferred default restricted, which only happens for an unsubscribed org with the gate on (subscribed orgs, anonymous fetches, and old gateways carry no marks). That one case lands on the free model instead of a premium default that errors on message one. The pi harness (no locked rendering) drops restricted models and falls back to the first served model.
• Locked pickers: restricted models stay listed, dimmed with a lock icon; clicking one opens the add-payment-method modal instead of selecting. Marks ride ACP option _meta (posthog.code/restrictedModel). Deliberately no codex model/list threading — codex's live options stay unmarked (the free tier has zero Codex-compatible models). A gated codex send used to die as a silent refusal — warning badge, no explanation; the adapter now rejects the prompt with the gateway's message so the feat(billing): classify gateway billing denials and rework the usage-limit modal for usage-based billing #3485 modal fires, same as Claude sends.

Why: without this, a free-tier org's first-run experience post-cutover is "default model errors immediately" — this makes the gate visible before the send instead of after it.

How did you test this?

Automated: typecheck green across agent/shared/workspace-server/harness/core/ui; pickAllowedModel unit tests (allowed/absent/restricted→newest-allowed/all-restricted/empty), gateway-models suite 28/28, codex adapter suite incl. a new billing-denial rejection test, UI billing+sessions suites 457/457, harness 651, shared 602 — all local. The agent/workspace-server integration suites can't run in this sandbox (they shell out to git commit, which is blocked here); relying on CI for those. Not covered: a visual pass over the locked picker items.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

---

Created with PostHog Code

[adboio]

• feat(billing): honor the gateway's free-tier model marks — authed fetches, safe defaults, locked pickers #3488 👈 (View in Graphite)
• feat(billing): usage-based billing surfaces — plans page, titlebar, announcement #3487
• feat(billing): classify gateway billing denials and rework the usage-limit modal for usage-based billing #3485
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 2351040.}

[greptile-apps]

Security Review

Authorization-dependent model restrictions are cached by authentication presence rather than principal identity. A process serving different organization tokens can therefore reuse one organization's entitlement response for another.

_{Reviews (1): Last reviewed commit: "fix(billing): carry the codex denial mes..." | Re-trigger Greptile}

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.

[adboio]

/trunk merge

[github-actions]

Could not verify team-posthog-code membership (GitHub API error). Auto-release is limited to Team PostHog Code members, so this will ship with the next scheduled release instead.