Add genmodels tool for OpenRouter model data

Fetches model metadata from the OpenRouter API and generates
pkg/llm/registry_gen.go with typed ModelDefinition entries.
Covers 9 providers: Anthropic, OpenAI, Google, xAI, Perplexity,
Amazon, Meta, Mistral, DeepSeek.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

internal/cmd/genmodels/main.go

@@ -0,0 +1,201 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"go/format"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+)
+
+const openRouterURL = "https://openrouter.ai/api/v1/models"
+
+var includedProviders = map[string]struct{}{
+	"anthropic":  {},
+	"openai":     {},
+	"google":     {},
+	"x-ai":       {},
+	"perplexity": {},
+	"amazon":     {},
+	"meta-llama": {},
+	"mistralai":  {},
+	"deepseek":   {},
+}
+
+var paramFieldMap = map[string]string{
+	"temperature":           "Temperature",
+	"top_p":                 "TopP",
+	"top_k":                 "TopK",
+	"frequency_penalty":     "FrequencyPenalty",
+	"presence_penalty":      "PresencePenalty",
+	"stop":                  "Stop",
+	"seed":                  "Seed",
+	"max_tokens":            "MaxTokens",
+	"max_completion_tokens": "MaxTokens",
+	"tool_choice":           "ToolChoice",
+	"parallel_tool_calls":   "ParallelToolCalls",
+	"response_format":       "ResponseFormat",
+	"structured_outputs":    "StructuredOutputs",
+	"reasoning":             "Reasoning",
+	"include_reasoning":     "Reasoning",
+}
+
+type (
+	openRouterResponse struct {
+		Data []openRouterModel `json:"data"`
+	}
+
+	openRouterModel struct {
+		ID          string `json:"id"`
+		Name        string `json:"name"`
+		ContextLen  int    `json:"context_length"`
+		TopProvider struct {
+			MaxCompletionTokens int `json:"max_completion_tokens"`
+		} `json:"top_provider"`
+		SupportedParams []string `json:"supported_parameters"`
+	}
+)
+
+const iscHeader = `// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+`
+
+func main() {
+	client := &http.Client{Timeout: 30 * time.Second}
+
+	resp, err := client.Get(openRouterURL)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "cannot fetch models: %v\n", err)
+		os.Exit(1)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		fmt.Fprintf(os.Stderr, "cannot fetch models: unexpected status %s\n", resp.Status)
+		os.Exit(1)
+	}
+
+	var result openRouterResponse
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		fmt.Fprintf(os.Stderr, "cannot decode response: %v\n", err)
+		os.Exit(1)
+	}
+
+	var buf strings.Builder
+	fmt.Fprintf(
+		&buf,
+		`%s// Code generated by genmodels; DO NOT EDIT.
+// Source: %s
+// Generated: %s
+
+package llm
+
+var generatedModels = []ModelDefinition{
+`,
+		iscHeader,
+		openRouterURL,
+		time.Now().UTC().Format(time.RFC3339),
+	)
+
+	var count int
+	for _, m := range result.Data {
+		provider := providerFromID(m.ID)
+		if _, ok := includedProviders[provider]; !ok {
+			continue
+		}
+
+		fmt.Fprintf(
+			&buf,
+			`	{
+		ID:              %q,
+		Name:            %q,
+		Provider:        %q,
+		ContextLength:   %d,
+		MaxOutputTokens: %d,
+		Supports: SupportedParameters{
+%s		},
+	},
+`,
+			m.ID,
+			m.Name,
+			provider,
+			m.ContextLen,
+			m.TopProvider.MaxCompletionTokens,
+			buildSupports(m.SupportedParams),
+		)
+		count++
+	}
+
+	buf.WriteString("}\n")
+
+	src, err := format.Source([]byte(buf.String()))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "cannot format generated code: %v\n", err)
+		os.Exit(1)
+	}
+
+	if err := os.WriteFile("registry_gen.go", src, 0644); err != nil {
+		fmt.Fprintf(os.Stderr, "cannot write file: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Fprintf(os.Stderr, "genmodels: wrote %d models to registry_gen.go\n", count)
+}
+
+func providerFromID(id string) string {
+	provider, _, ok := strings.Cut(id, "/")
+	if ok {
+		return provider
+	}
+	return ""
+}
+
+func buildSupports(params []string) string {
+	fields := make(map[string]bool)
+	for _, p := range params {
+		if field, ok := paramFieldMap[p]; ok {
+			fields[field] = true
+		}
+	}
+
+	var buf strings.Builder
+	fieldNames := []string{
+		"Temperature", "TopP", "TopK", "FrequencyPenalty", "PresencePenalty",
+		"Stop", "Seed", "MaxTokens", "ToolChoice", "ParallelToolCalls",
+		"ResponseFormat", "StructuredOutputs", "Reasoning",
+	}
+	for _, f := range fieldNames {
+		if fields[f] {
+			fmt.Fprintf(&buf, "			%s: true,\n", f)
+		}
+	}
+	return buf.String()
+}