feat: regex support for model-mappings

internal/api/modules/amp/model_mapping.go

@@ -3,6 +3,7 @@
 package amp
 
 import (
+    "regexp"
 	"strings"
 	"sync"
 
@@ -26,13 +27,15 @@ type ModelMapper interface {
 // DefaultModelMapper implements ModelMapper with thread-safe mapping storage.
 type DefaultModelMapper struct {
 	mu       sync.RWMutex
-	mappings map[string]string // from -> to (normalized lowercase keys)
+    mappings map[string]string // exact: from -> to (normalized lowercase keys)
+    regexps  []regexMapping    // regex rules evaluated in order
 }
 
 // NewModelMapper creates a new model mapper with the given initial mappings.
 func NewModelMapper(mappings []config.AmpModelMapping) *DefaultModelMapper {
 	m := &DefaultModelMapper{
-		mappings: make(map[string]string),
+        mappings: make(map[string]string),
+        regexps:  nil,
 	}
 	m.UpdateMappings(mappings)
 	return m
@@ -55,7 +58,18 @@ func (m *DefaultModelMapper) MapModel(requestedModel string) string {
 	// Check for direct mapping
 	targetModel, exists := m.mappings[normalizedRequest]
 	if !exists {
-		return ""
+        // Try regex mappings in order
+        base, _ := util.NormalizeThinkingModel(requestedModel)
+        for _, rm := range m.regexps {
+            if rm.re.MatchString(requestedModel) || (base != "" && rm.re.MatchString(base)) {
+                targetModel = rm.to
+                exists = true
+                break
+            }
+        }
+        if !exists {
+            return ""
+        }
 	}
 
 	// Verify target model has available providers
@@ -77,7 +91,8 @@ func (m *DefaultModelMapper) UpdateMappings(mappings []config.AmpModelMapping) {
 	defer m.mu.Unlock()
 
 	// Clear and rebuild mappings
-	m.mappings = make(map[string]string, len(mappings))
+    m.mappings = make(map[string]string)
+    m.regexps = m.regexps[:0]
 
 	for _, mapping := range mappings {
 		from := strings.TrimSpace(mapping.From)
@@ -88,16 +103,30 @@ func (m *DefaultModelMapper) UpdateMappings(mappings []config.AmpModelMapping) {
 			continue
 		}
 
-		// Store with normalized lowercase key for case-insensitive lookup
-		normalizedFrom := strings.ToLower(from)
-		m.mappings[normalizedFrom] = to
-
-		log.Debugf("amp model mapping registered: %s -> %s", from, to)
+        if mapping.Regex {
+            // Compile case-insensitive regex; wrap with (?i) to match behavior of exact lookups
+            pattern := "(?i)" + from
+            re, err := regexp.Compile(pattern)
+            if err != nil {
+                log.Warnf("amp model mapping: invalid regex %q: %v", from, err)
+                continue
+            }
+            m.regexps = append(m.regexps, regexMapping{re: re, to: to})
+            log.Debugf("amp model regex mapping registered: /%s/ -> %s", from, to)
+        } else {
+            // Store with normalized lowercase key for case-insensitive lookup
+            normalizedFrom := strings.ToLower(from)
+            m.mappings[normalizedFrom] = to
+            log.Debugf("amp model mapping registered: %s -> %s", from, to)
+        }
 	}
 
 	if len(m.mappings) > 0 {
 		log.Infof("amp model mapping: loaded %d mapping(s)", len(m.mappings))
 	}
+    if n := len(m.regexps); n > 0 {
+        log.Infof("amp model mapping: loaded %d regex mapping(s)", n)
+    }
 }
 
 // GetMappings returns a copy of current mappings (for debugging/status).
@@ -111,3 +140,8 @@ func (m *DefaultModelMapper) GetMappings() map[string]string {
 	}
 	return result
 }
+
+type regexMapping struct {
+    re *regexp.Regexp
+    to string
+}