GPT 5.5 context limits are not respected

[asaf-genie]

Description

opencode uses hard coded context limits values for gpt-5.5, ignoring values set in opencode.jsonc.

I suspect it's due to PR #24212 which added this to codex.ts:

// gpt-5.5 models temporarily have restricted context window size for codex plans
if (model.id.includes("gpt-5.5")) {
  model.limit = {
    context: 400_000,
    //@ts-expect-error incorrect type for v1 sdk but works
    input: 272_000,
    output: 128_000,
  }
}

It should probably either overwrite only when the values are not specified in the config, or use max(400_000, model.limit.context) (same for input/output) to allow lower values (which is useful because gpt-5.5 is very expensive)

Plugins

None

OpenCode version

1.14.28

Steps to reproduce

1. Add this to ~/.config/opencode/opencode.jsonc in provider.openai.models:

"gpt-5.4": {
  "limit": {
    "context": 200000,
    "input": 150000,
    "output": 50000,
  },
},
"gpt-5.5": {
  "limit": {
    "context": 200000,
    "input": 150000,
    "output": 50000,
  },
},

2. Run opencode models openai --verbose and check context limits for both models. gpt-5.4 will respect the overrides, gpt-5.5 will not. Alternatively, start a conversation with gpt-5.5, you'll see that the context window stats are relative to 400k context window not 200k.

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Operating System

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Terminal

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[github-actions]

This issue might be a duplicate of (or closely related to) an existing issue. Please check:

• GPT-5.5 Codex context limit dropped to 400k but uses API context limit (1M) causing "exceeds the context window of this model" errors #24171: Same root cause (PR fix: ensure gpt-5.5 compacts at correct context size when using openai oauth #24212 hardcoding gpt-5.5 context limits in codex.ts). That issue reports that the 400k Codex limit overrides the larger API limit, while this issue reports that the hardcoded values override user-configured lower limits. They are distinct symptoms but share the same underlying code.