pi-model-filter

Filter and block models from any provider in pi via declarative allow/block rules.

Hide unwanted GitHub Copilot models, enforce global allowlists, block by reasoning capability or context window size — all through a simple JSON config.

Install

pi install pi-model-filter

Configuration

Create model-filter.json in pi's agent directory (typically ~/.pi/agent/model-filter.json):

Schema

interface FilterRule {
  provider: string;      // "*" = any provider
  action: "allow" | "block";
  match: {
    ids?: string[];                    // exact model ID match (OR)
    patterns?: string[];               // glob patterns (OR), supports * and ?
    reasoning?: boolean;               // match reasoning capability
    contextWindow?: { min?: number; max?: number }; // match context window size
  };
}

interface FilterConfig {
  rules: FilterRule[];                 // evaluated top-to-bottom, first match wins
  defaultAction: "allow" | "block";   // default: "allow"
}

Rule evaluation

• Rules are evaluated top to bottom — first matching rule wins.
• Within a match field, alternatives are OR'd (e.g., ids: ["a", "b"] matches either).
• Across different match fields, conditions are AND'd (e.g., ids + reasoning must both match).
• If no rule matches, defaultAction applies.
• Invalid or missing config fails open: all models pass through with a warning.

Examples

Allowlist for Copilot, leave other providers untouched:

{
  "rules": [
    {
      "provider": "github-copilot",
      "action": "allow",
      "match": { "ids": ["claude-opus-4.6", "gpt-5.4", "gpt-5.5"] }
    },
    {
      "provider": "github-copilot",
      "action": "block",
      "match": { "patterns": ["*"] }
    }
  ],
  "defaultAction": "allow"
}

Strict global allowlist:

{
  "rules": [
    {
      "provider": "github-copilot",
      "action": "allow",
      "match": { "ids": ["claude-opus-4.6", "gpt-5.4", "gpt-5.5"] }
    }
  ],
  "defaultAction": "block"
}

Block non-reasoning models:

{
  "rules": [
    { "provider": "*", "action": "block", "match": { "reasoning": false } }
  ],
  "defaultAction": "allow"
}

Block small context windows:

{
  "rules": [
    { "provider": "*", "action": "block", "match": { "contextWindow": { "max": 150000 } } }
  ],
  "defaultAction": "allow"
}

How it works

The extension patches ModelRegistry.prototype at load time (before startup model resolution) so filtered models are hidden from /model, --model CLI flags, and request auth resolution. It does not mutate the registry's internal model array — filtering happens on method results.

Failure behavior

• Missing or invalid config: all models pass through, warning logged.
• pi internals change: extension detects missing methods and disables itself with a warning.
• Hot reload: editing model-filter.json takes effect without restarting pi.