Models

The plugin auto-registers the following, and they appear in the model picker with no extra config: Haiku 4.5, Sonnet 4.5/4.6/5/5.5, Opus 4.5/4.6/4.7/4.8/5/5.5 (plus three fast-mode Opus entries), Fable 5/5.1 and Mythos 5/5.1, each except Haiku carrying low / medium / high / xhigh / max reasoning variants.

ID	Display name	Context	Output	Reasoning variants	Price ×
claude-haiku-4-5	Claude Haiku 4.5	200k	64,000	–	1×
claude-sonnet-4-5	Claude Sonnet 4.5	200k	64,000	low/medium/high/xhigh/max	3×
claude-sonnet-4-6	Claude Sonnet 4.6	1M	128,000	low/medium/high/xhigh/max	3×
claude-sonnet-5	Claude Sonnet 5	1M	128,000	low/medium/high/xhigh/max	2×
claude-sonnet-5-5	Claude Sonnet 5.5	1M	128,000	low/medium/high/xhigh/max	2×
claude-opus-4-5	Claude Opus 4.5	200k	64,000	low/medium/high/xhigh/max	5×
claude-opus-4-6	Claude Opus 4.6	1M	128,000	low/medium/high/xhigh/max	5×
claude-opus-4-7	Claude Opus 4.7	1M	128,000	low/medium/high/xhigh/max	5×
claude-opus-4-8	Claude Opus 4.8	1M	128,000	low/medium/high/xhigh/max	5×
claude-opus-4-8-fast	Claude Opus 4.8 Fast	1M	128,000	low/medium/high/xhigh/max	10×
claude-opus-5	Claude Opus 5	1M	128,000	low/medium/high/xhigh/max	5×
claude-opus-5-fast	Claude Opus 5 Fast	1M	128,000	low/medium/high/xhigh/max	10×
claude-opus-5-5	Claude Opus 5.5	1M	128,000	low/medium/high/xhigh/max	4×
claude-opus-5-5-fast	Claude Opus 5.5 Fast	1M	128,000	low/medium/high/xhigh/max	8×
claude-fable-5	Claude Fable 5	1M	128,000	low/medium/high/xhigh/max	10×
claude-fable-5-1	Claude Fable 5.1	1M	128,000	low/medium/high/xhigh/max	10×
claude-mythos-5	Claude Mythos 5	1M	128,000	low/medium/high/xhigh/max	10×
claude-mythos-5-1	Claude Mythos 5.1	1M	128,000	low/medium/high/xhigh/max	10×

claude-mythos-5 and claude-mythos-5-1 are Mythos-class counterparts to the corresponding Fable models, but without safety classifiers, and are limited availability via Project Glasswing. They’re registered unconditionally; if your Claude account lacks access, claude --model just errors. Use the corresponding generally available claude-fable-5 or claude-fable-5-1 otherwise.

Capabilities for every model: text + image input, text output, tool use, attachments. No temperature control, no PDF/audio/video, no interleaved streaming.

Price × is each model’s per-token list price relative to Haiku, the cheapest model. It’s derived exactly from Anthropic’s published pricing (input and output ratios both come out the same: Haiku $1/$5 = 1×, Sonnet 5 and 5.5 $2/$10 = 2×, Sonnet 4.5/4.6 $3/$15 = 3×, Opus 5.5 $4/$20 = 4×, Opus $5/$25 = 5×, Opus 5.5 fast mode $8/$40 = 8×, Fable/Mythos 5 and 5.1 / Opus 5 and 4.8 fast mode $10/$50 = 10×). So Fable/Mythos 5 and 5.1, and fast-mode Opus 5 and 4.8, all cost 2× standard Opus 5, and fast mode is 2× the standard price on every Opus that offers it. The same multiplier is shown as a (N×) suffix on the display name in opencode’s model picker, since opencode has no dedicated multiplier field. On a flat Max/Pro subscription it doubles as a rough guide to how fast each model drains your usage limit.

Fable 5.1 and Mythos 5.1 keep the same $10/M input and $50/M output rates as 5.0, but cache reads cost $0.25/M instead of $1/M. Their cache-write rate remains $12.50/M.

Sonnet 5 and Sonnet 5.5 are $2/M input and $10/M output, with cache writes at $2.50/M and cache reads at $0.20/M. Sonnet 5’s price was announced as introductory until 2026-08-31, but Anthropic cancelled the increase to $3/$15, so $2/$10 is its standard price. Sonnet 5.5 runs on any recent Claude Code, but 2.1.284 is the first release that knows it. An older CLI still serves it, on fallback limits (a 200k context window instead of 1M, and an estimated cost). The plugin warns once when the CLI reports that, and claude update fixes it.

Opus 5.5 is priced below the Opus line at $4/M input and $20/M output, with cache writes at $5/M and cache reads at $0.20/M (0.05× input rather than the usual 0.1×). It needs Claude Code 2.1.280 or newer: the API rejects it from an older CLI with a 400 naming that floor, which shows up as a failed turn.

The model ID is passed straight through to claude --model, so anything Claude Code accepts works. The three -fast IDs are the one exception, described below.

Fast mode

claude-opus-5-5-fast, claude-opus-5-fast and claude-opus-4-8-fast run the same models at up to 2.5× the output tokens per second, at 2× the price ($8/M input, $40/M output for Opus 5.5, the 8× column; $10/M input, $50/M output for Opus 5 and 4.8, the 10× column). Pick them in the model selector like any other model.

The -fast suffix is this plugin’s own marker, not a model name Anthropic serves. The plugin strips it and spawns claude --model claude-opus-5 --settings '{"fastMode":true}', because that settings layer is the only way to opt a headless (--print) session into fast mode: there is no --fast flag, and the old claude-opus-4-6-fast style model names are retired. Requires Claude Code 2.1.220+; below that the plugin skips the opt-in and you get standard speed.

Fast mode is not available everywhere, and it fails soft: an ineligible account drops back to standard speed with no error. Known blockers:

• Usage credits are off. The most common one. Run /usage-credits in an interactive claude session to enable them.
• Not first-party. Fast mode is Anthropic-API-only; Bedrock, Vertex, and Foundry are excluded.
• Free tier, or an organization that has turned fast mode off.
• Cooldown. Fast mode has its own rate limit; after a hit, Claude Code falls back to standard until it clears.
• CLAUDE_CODE_DISABLE_FAST_MODE=1 in the environment turns it off outright.

Because a downgrade is otherwise invisible, and because the picker shows these IDs at 10× regardless, the plugin logs a warning (once per reason) when a fast turn actually ran at standard speed, naming the reason. If you see it, switch to the non-fast ID so the picker’s price matches your bill.

Picking a variant

Variants set the underlying reasoning effort. They’re regular opencode model variants, so pick them in the model selector. If you’d previously declared variants in your project’s opencode.json, they’re merged on top of the defaults so nothing gets lost.

Overriding model metadata

To rename a model, change a limit, or add a custom one:

{
  "plugin": ["@khalilgharbaoui/opencode-claude-code-plugin"],
  "provider": {
    "claude-code": {
      "models": {
        "claude-sonnet-4-6": {
          "name": "Sonnet (custom)",
          "limit": { "context": 1000000, "output": 32768 }
        }
      }
    }
  }
}

Anything you supply is merged on top of the defaults; you don’t need to redeclare every model.