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pigo/internal/provider/infer.go

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+// This file implements model-name → provider inference (US: auto-infer provider
+// from --model alone). When a user supplies only --model, with no --provider,
+// --protocol, or --base-url, pigo tries to guess the owning provider from the
+// model id's well-known name prefix (e.g. "claude-*" → anthropic, "deepseek-*"
+// → deepseek). This lets `pigo -m claude-opus-4-8` reach the Anthropic API
+// without the user spelling out the provider or its wire protocol.
+//
+// The mapping is deliberately conservative: only names that unambiguously
+// identify a single built-in provider are inferred. Ambiguous families served
+// by many gateways (notably "llama-*", "qwq-*", "gemma-*", "mixtral-*") are NOT
+// inferred — they return ok=false so the caller falls through to its existing
+// default (OpenRouter), which is the safe, unchanged behavior.
+//
+// Every provider name returned here is guaranteed to exist in providerRegistry
+// (enforced by a test), so callers can hand the result straight to the
+// registry-driven resolution path.
+package provider
+
+import "strings"
+
+// modelPrefixProvider maps a lowercase model-name prefix to the built-in
+// provider name that serves that family. Order matters: the table is scanned
+// top-to-bottom and the FIRST matching prefix wins, so list more specific
+// prefixes before shorter ones that would also match.
+//
+// Each provider name here must be present in providerRegistry (registry.go).
+var modelPrefixProvider = []struct {
+	prefix   string
+	provider string
+}{
+	{"claude-", "anthropic"},
+	{"gpt-", "openai"},
+	{"o1-", "openai"},
+	{"o3-", "openai"},
+	{"o4-", "openai"},
+	{"gemini-", "google"},
+	{"deepseek-", "deepseek"},
+	{"glm-", "zai"},
+	{"kimi-", "moonshotai"},
+	{"moonshot-", "moonshotai"},
+	{"qwen-", "dashscope"},
+	{"ernie-", "qianfan"},
+	{"doubao-", "volcengine"},
+	{"grok-", "xai"},
+	{"mistral-", "mistral"},
+	{"codestral-", "mistral"},
+	{"devstral-", "mistral"},
+	{"hunyuan-", "hunyuan"},
+	{"minimax-", "minimax"},
+	{"mimo-", "xiaomi"},
+}
+
+// InferProviderFromModel guesses the built-in provider name that serves a given
+// model id, based on the id's well-known name prefix. It returns the provider
+// name and ok=true on a confident match, or ("", false) when the id is unknown
+// or ambiguous (served by multiple gateways). Matching is case-insensitive.
+//
+// The returned name is always a valid entry in providerRegistry. Callers should
+// use it only when no explicit --provider/--protocol/--base-url was given; those
+// flags take precedence over any inference.
+func InferProviderFromModel(model string) (string, bool) {
+	id := strings.ToLower(strings.TrimSpace(model))
+	if id == "" {
+		return "", false
+	}
+	// A "provider/model" style id (e.g. "openai/gpt-4o") is an OpenRouter-style
+	// routed id, not a bare model name — leave those to the caller's preset/
+	// prefix handling rather than inferring from the leading segment.
+	if strings.Contains(id, "/") {
+		return "", false
+	}
+	for _, m := range modelPrefixProvider {
+		if strings.HasPrefix(id, m.prefix) {
+			return m.provider, true
+		}
+	}
+	return "", false
+}