Closes#7919. Wire claude-haiku-5-5 (released 2026-10-07) across model
registry, effort catalog, pricing, billing, validation and Codex
descriptors, following the opus-5-5/sonnet-5-5 template and the official
migration guide + overview specs.
- registry: DefaultModels entry (fixed ID, no date suffix per guide)
- effort: full low/medium/high/xhigh/max family + IsHaiku55 +
claude-haiku-5.5 dotted normalization (official default: medium)
- pricing catalog: 1M/128k limits, base (<=100k) prices and
*_above_100k_tokens absolute prices; the existing ladder derivation
yields threshold=100000 with uniform 5x multipliers, matching the
official two-tier table exactly (cache tiers follow input x5)
- billing/pricing fallbacks carry the same tier so a missing catalog
entry can never silently bill >100k prompts at base rate
- validation: adaptive-only thinking (enabled always 400; disabled 400
at xhigh/max), sonnet-style sampling locks, temp+top_p combo rejected,
forced tool_choice explicitly allowed (differs from opus/sonnet)
- oauth mimicry: skip temperature:1 top-up when top_p is present on
sampling-locked models (sonnet-5-5 included), otherwise the gateway
manufactures the temp+top_p 400 itself
- toolset beta filter + Codex 1M context cover haiku-5-5
- Bedrock/Antigravity mappings intentionally left out (no 5.5 entries
exist there at all, same as opus-5-5); Vertex passes the fixed ID
through untouched
- Accept fast|priority (canonical priority), flex|auto|default|scale on
/v1/responses and /v1/chat/completions; reject unknown/empty/non-string
with HTTP 400; omitted and null stay compatible.
- Propagate service_tier through JSON/SSE, Responses<->Chat conversions,
fallback paths and HTTP->upstream WebSocket bridge.
- Billing prefers the upstream terminal tier; the outbound (policy-
transformed) tier is used only when upstream omits the field.
Explicit upstream default bills Standard even when Fast was requested.
- Pricing: Fast premium 2x Standard for gpt-5.6-sol/terra/luna and
gpt-5.4; 2.5x for gpt-5.5; channel FastMultiplier stays authoritative.
- Live verification (official Codex 0.149.0 + gateway, HTTP & WS):
upstream ChatGPT backend may return terminal default even when the
account catalog advertises priority; billing follows the actual tier.
Wesley Liddick