fix(opencode): lower Claude Sonnet 5.5 cache read to $0.10 to match Anthropic - #13175

Summary

OpenCode Zen still prices Claude Sonnet 5.5 cache reads at $0.20/MTok. Anthropic halved them to $0.10/MTok on 2026-10-07, and providers/anthropic/models/claude-sonnet-5-5.toml was updated the same day in #9035, but the Zen entry kept the launch price. Zen passes provider prices through at cost, so this sets Zen's cache-read price to $0.10.

Changes

• providers/opencode/models/claude-sonnet-5-5.toml: [cost.text.input] cache.read 0.2 → 0.1, plus a header comment citing the source. Input, output and cache write are unchanged.

Sources

• https://www.anthropic.com/claude-haiku-5-5 (Oct 7, 2026, "Further updates"): "starting today, we're lowering the price of cache reads on Claude Sonnet 5.5. Cache reads now cost 50% less: $0.10 per million tokens rather than $0.20."
• https://platform.claude.com/docs/en/about-claude/pricing: Sonnet 5.5 cache hits are $0.10/MTok (0.05x base input).
• https://platform.claude.com/docs/en/models/sonnet-5-5/overview: cache read $0.10/MTok.

Validation

bun validate passes. bun run v1:check reports one v1 change, the intended price fix:

Changed v1 fields (count, change, examples):
     1  api cost.cache_read: 0.2 -> 0.1   [opencode/claude-sonnet-5-5]

As a sourced price fix inside the v1 schema, this needs maintainer approval.

Notes

• I compared every Claude model in providers/opencode with its providers/anthropic price in the live api.json. Sonnet 5.5 is the only one that differs.
• The Console pricing page in anomalyco/opencode (services/site/src/docs/content/console/models.mdx) also lists $0.20 and needs a matching update.