fix(copilot): map hyphen-style Claude model names to dot-style upstream IDs

Clients (Claude Code, Cursor, etc.) request Claude models with hyphen-only
IDs like 'claude-haiku-4-5', but GitHub Copilot publishes them with dots
(e.g. 'claude-haiku-4.5'). Without alias mapping, requests fail with:
  502 unknown provider for model claude-haiku-4-5

Three additions:

1. internal/config/oauth_model_alias_defaults.go (new): static defaults
   mapping dot IDs to hyphen aliases for the 6 known Claude Copilot
   models, plus GitHubCopilotAliasesFromModels() helper for dynamic
   alias generation from fetched model lists.

2. internal/config/config.go SanitizeOAuthModelAlias: inject the
   github-copilot defaults if the user has not configured any
   github-copilot aliases. Runs before the existing dedup pass.

3. sdk/cliproxy/auth/oauth_model_alias.go OAuthModelAliasChannel: add
   'github-copilot' to the list of channels where aliases are honored.
   Previously fell to the default branch and aliases were ignored.

Origin: ported from the archived CLIProxyAPIPlus fork's
internal/config/oauth_model_alias_defaults.go (Kiro defaults skipped).

Author: conversun

internal/config/config.go

@@ -830,7 +830,26 @@ func (cfg *Config) SanitizeClaudeHeaderDefaults() {
 // It trims whitespace, normalizes channel keys to lower-case, drops empty entries,
 // allows multiple aliases per upstream name, and ensures aliases are unique within each channel.
 func (cfg *Config) SanitizeOAuthModelAlias() {
-	if cfg == nil || len(cfg.OAuthModelAlias) == 0 {
+	if cfg == nil {
+		return
+	}
+	// Inject channel defaults when the channel is absent in user config.
+	// Presence is checked case-insensitively.
+	if cfg.OAuthModelAlias == nil {
+		cfg.OAuthModelAlias = make(map[string][]OAuthModelAlias)
+	}
+	hasChannel := func(channel string) bool {
+		for k := range cfg.OAuthModelAlias {
+			if strings.EqualFold(strings.TrimSpace(k), channel) {
+				return true
+			}
+		}
+		return false
+	}
+	if !hasChannel("github-copilot") {
+		cfg.OAuthModelAlias["github-copilot"] = defaultGitHubCopilotAliases()
+	}
+	if len(cfg.OAuthModelAlias) == 0 {
 		return
 	}
 	out := make(map[string][]OAuthModelAlias, len(cfg.OAuthModelAlias))

internal/config/oauth_model_alias_defaults.go

@@ -0,0 +1,41 @@
+package config
+
+import "strings"
+
+// defaultGitHubCopilotAliases returns default oauth-model-alias entries for
+// GitHub Copilot Claude models. It exposes hyphen-style IDs used by clients
+// (e.g. claude-haiku-4-5) in addition to the dot-style IDs that GitHub
+// Copilot upstream actually publishes (e.g. claude-haiku-4.5).
+func defaultGitHubCopilotAliases() []OAuthModelAlias {
+	return []OAuthModelAlias{
+		{Name: "claude-haiku-4.5", Alias: "claude-haiku-4-5", Fork: true},
+		{Name: "claude-opus-4.1", Alias: "claude-opus-4-1", Fork: true},
+		{Name: "claude-opus-4.5", Alias: "claude-opus-4-5", Fork: true},
+		{Name: "claude-opus-4.6", Alias: "claude-opus-4-6", Fork: true},
+		{Name: "claude-sonnet-4.5", Alias: "claude-sonnet-4-5", Fork: true},
+		{Name: "claude-sonnet-4.6", Alias: "claude-sonnet-4-6", Fork: true},
+	}
+}
+
+// GitHubCopilotAliasesFromModels generates oauth-model-alias entries from a
+// dynamic list of model IDs fetched from the Copilot API. It auto-creates
+// hyphen aliases for any model whose ID contains a dot (e.g.
+// "claude-opus-4.7" -> "claude-opus-4-7"), which is the convention used by
+// Claude models served via GitHub Copilot.
+func GitHubCopilotAliasesFromModels(modelIDs []string) []OAuthModelAlias {
+	var aliases []OAuthModelAlias
+	seen := make(map[string]struct{})
+	for _, id := range modelIDs {
+		if !strings.Contains(id, ".") {
+			continue
+		}
+		hyphenID := strings.ReplaceAll(id, ".", "-")
+		key := id + "->" + hyphenID
+		if _, ok := seen[key]; ok {
+			continue
+		}
+		seen[key] = struct{}{}
+		aliases = append(aliases, OAuthModelAlias{Name: id, Alias: hyphenID, Fork: true})
+	}
+	return aliases
+}

sdk/cliproxy/auth/oauth_model_alias.go

@@ -289,7 +289,7 @@ func OAuthModelAliasChannel(provider, authKind string) string {
 			return ""
 		}
 		return "codex"
-	case "gemini-cli", "aistudio", "antigravity", "kimi":
+	case "gemini-cli", "aistudio", "antigravity", "kimi", "github-copilot":
 		return provider
 	default:
 		return ""