Add GET/POST /settings handlers with injected applier

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/web/settings_handlers.go

@@ -0,0 +1,61 @@
+package web
+
+import (
+	"net/http"
+
+	"antidrift/internal/settings"
+
+	"github.com/gin-gonic/gin"
+)
+
+// SetSettings injects the persisted settings, their file path, and the applier
+// closure (built by main, which owns adapter construction). Mirrors the
+// controller's Set* injection so web never imports ai/tasks/knowledge.
+func (s *Server) SetSettings(path string, current settings.Settings, apply func(settings.Settings) error) {
+	s.settingsMu.Lock()
+	s.settingsPath = path
+	s.settings = current
+	s.applyFn = apply
+	s.settingsMu.Unlock()
+}
+
+func (s *Server) handleGetSettings(c *gin.Context) {
+	s.settingsMu.Lock()
+	cur := s.settings
+	s.settingsMu.Unlock()
+	c.JSON(http.StatusOK, cur)
+}
+
+// handlePostSettings validates-and-applies atomically, then persists. The applier
+// checks the backend before mutating any state, so an invalid backend yields 400
+// with nothing saved and the prior wiring intact.
+func (s *Server) handlePostSettings(c *gin.Context) {
+	var req settings.Settings
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid json"})
+		return
+	}
+	s.settingsMu.Lock()
+	apply := s.applyFn
+	path := s.settingsPath
+	s.settingsMu.Unlock()
+	if apply == nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "settings not wired"})
+		return
+	}
+	if err := apply(req); err != nil {
+		// Apply validates the backend before mutating anything, so any error
+		// (invalid backend or otherwise) means nothing changed; surface it as 400.
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	if err := settings.Save(path, req); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	s.settingsMu.Lock()
+	s.settings = req
+	s.settingsMu.Unlock()
+	s.broadcast()
+	c.JSON(http.StatusOK, req)
+}