diff --git a/docs/SKILLS.md b/docs/SKILLS.md
index 733028dca9..531db293c8 100644
--- a/docs/SKILLS.md
+++ b/docs/SKILLS.md
@@ -179,6 +179,10 @@ When the listing changes:
   this project; add `--global` to apply everywhere.
 - `reasonix doctor` reports skill health warnings, such as a missing
   description or a required capability that is not available.
+- The terminal UI and Studio show discovery diagnostics as renderer-managed
+  notices, including new diagnostics discovered while completing a slash command.
+  Identical diagnostics are shown once per skill store; changed diagnostics remain
+  visible. Noninteractive commands keep their stderr diagnostics.
 
 ```toml
 [skills]
diff --git a/internal/assembly/boot/composition_live_skills.go b/internal/assembly/boot/composition_live_skills.go
index d3806d9459..55b568a94b 100644
--- a/internal/assembly/boot/composition_live_skills.go
+++ b/internal/assembly/boot/composition_live_skills.go
@@ -16,7 +16,7 @@ func (b *builder) liveSkillSource() func() *skill.Store {
 			ProjectRoot: b.root, ReasonixHomeDir: b.roots.Home(), CustomPaths: cfg.SkillCustomPaths(),
 			PluginPaths: cfg.PluginPackageSkillOwners(), PluginAgentPaths: cfg.PluginPackageAgentOwners(),
 			ExcludedPaths: cfg.SkillExcludedPaths(), DisabledNames: func() []string { return disabledSkillNames(cfg, b.root) },
-			MaxDepth: cfg.SkillMaxDepth(), Stderr: io.Discard, SuppressWarnings: true,
+			MaxDepth: cfg.SkillMaxDepth(), Stderr: io.Discard, SuppressWarnings: cfg.Skills.SuppressWarnings,
 		})
 	}
 }
diff --git a/internal/assembly/boot/options.go b/internal/assembly/boot/options.go
index 7fafbdfb9a..4cb5aad478 100644
--- a/internal/assembly/boot/options.go
+++ b/internal/assembly/boot/options.go
@@ -66,6 +66,9 @@ type Options struct {
 	// Interactive terminals must pass a private writer (or io.Discard) so
 	// background output cannot corrupt the TUI's raw mode.
 	Stderr io.Writer
+	// DiagnosticSink receives skill discovery warnings as renderer-managed notices.
+	// Nil preserves the noninteractive stderr destination.
+	DiagnosticSink event.Sink
 	// OnPhase receives completed assembly timings synchronously, including on a later failure.
 	OnPhase func(Phase)
 	// Project root for config, skills, memory, commands, hooks, and tool
diff --git a/internal/assembly/boot/skill_diagnostics.go b/internal/assembly/boot/skill_diagnostics.go
new file mode 100644
index 0000000000..01bef253cf
--- /dev/null
+++ b/internal/assembly/boot/skill_diagnostics.go
@@ -0,0 +1,14 @@
+package boot
+
+import (
+	"strings"
+
+	"reasonix/internal/contract/event"
+)
+
+type skillDiagnosticWriter struct{ sink event.Sink }
+
+func (w skillDiagnosticWriter) Write(p []byte) (int, error) {
+	report(w.sink, event.Event{Level: event.LevelWarn, Text: strings.TrimRight(string(p), "\r\n")})
+	return len(p), nil
+}
diff --git a/internal/assembly/boot/skill_diagnostics_test.go b/internal/assembly/boot/skill_diagnostics_test.go
new file mode 100644
index 0000000000..64cabfee4b
--- /dev/null
+++ b/internal/assembly/boot/skill_diagnostics_test.go
@@ -0,0 +1,111 @@
+package boot
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"reasonix/internal/contract/config"
+	"reasonix/internal/contract/event"
+	"reasonix/internal/ext/skill"
+)
+
+func TestSkillDiagnosticsReachRendererAcrossRediscovery(t *testing.T) {
+	root := t.TempDir()
+	home := t.TempDir()
+	t.Setenv("REASONIX_HOME", home)
+	var raw bytes.Buffer
+	var notices []event.Event
+	opts := Options{Stderr: &raw, DiagnosticSink: event.FuncSink(func(e event.Event) { notices = append(notices, e) })}
+	assembly := buildSkillAssembly(opts, &config.Config{}, root, true, "")
+	notices = nil
+	raw.Reset()
+	dir := filepath.Join(root, ".reasonix", "skills", "new-warning")
+	if err := os.MkdirAll(dir, 0700); err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(dir, "SKILL.md")
+	write := func(name string) {
+		t.Helper()
+		if err := os.WriteFile(path, []byte("---\nname: "+name+"\n---\nA runtime skill.\n"), 0600); err != nil {
+			t.Fatal(err)
+		}
+	}
+	write("new-warning")
+	assembly.store.SlashList()
+	if raw.Len() != 0 {
+		t.Fatalf("runtime diagnostic overwrote terminal stderr: %s", raw.String())
+	}
+	if len(notices) != 1 || notices[0].Kind != event.Notice || notices[0].Level != event.LevelWarn || !strings.Contains(notices[0].Text, "new-warning") {
+		t.Fatalf("renderer notices = %+v", notices)
+	}
+	assembly.store.SlashList()
+	if len(notices) != 1 {
+		t.Fatalf("identical diagnostic repeated: %+v", notices)
+	}
+	write("changed-warning")
+	time.Sleep(2100 * time.Millisecond)
+	assembly.store.SlashList()
+	if len(notices) != 2 || !strings.Contains(notices[1].Text, "changed-warning") {
+		t.Fatalf("changed diagnostic lost: %+v", notices)
+	}
+	assembly.store.ConfigureDiscoverySource(func() *skill.Store {
+		return skill.New(skill.Options{ProjectRoot: root, ReasonixHomeDir: home, Stderr: io.Discard})
+	})
+	assembly.store.SlashList()
+	if len(notices) != 2 {
+		t.Fatalf("live source repeated diagnostic: %+v", notices)
+	}
+	write("live-warning")
+	assembly.store.SlashList()
+	if len(notices) != 3 || !strings.Contains(notices[2].Text, "live-warning") {
+		t.Fatalf("live diagnostic lost: %+v", notices)
+	}
+}
+
+func TestSkillDiagnosticDestinationsAtStartup(t *testing.T) {
+	for _, interactive := range []bool{false, true} {
+		for _, suppressed := range []bool{false, true} {
+			t.Run(fmt.Sprintf("renderer=%t/suppressed=%t", interactive, suppressed), func(t *testing.T) {
+				root := t.TempDir()
+				t.Setenv("REASONIX_HOME", t.TempDir())
+				dir := filepath.Join(root, ".reasonix", "skills", "startup-warning")
+				if err := os.MkdirAll(dir, 0700); err != nil {
+					t.Fatal(err)
+				}
+				if err := os.WriteFile(filepath.Join(dir, "SKILL.md"), []byte("---\nname: startup-warning\n---\nBody.\n"), 0600); err != nil {
+					t.Fatal(err)
+				}
+				var raw bytes.Buffer
+				var notices []event.Event
+				opts := Options{Stderr: &raw}
+				if interactive {
+					opts.DiagnosticSink = event.FuncSink(func(e event.Event) { notices = append(notices, e) })
+				}
+				cfg := &config.Config{}
+				cfg.Skills.SuppressWarnings = suppressed
+				assembly := buildSkillAssembly(opts, cfg, root, true, "")
+				assembly.store.SlashList()
+				if interactive && raw.Len() != 0 {
+					t.Fatalf("raw stderr: %s", raw.String())
+				}
+				if suppressed {
+					if len(notices) != 0 || raw.Len() != 0 {
+						t.Fatalf("suppressed diagnostic emitted: %+v %q", notices, raw.String())
+					}
+				} else if interactive {
+					if len(notices) != 1 {
+						t.Fatalf("startup notices = %+v", notices)
+					}
+				} else if !strings.Contains(raw.String(), "startup-warning") {
+					t.Fatalf("missing noninteractive stderr: %q", raw.String())
+				}
+			})
+		}
+	}
+}
diff --git a/internal/assembly/boot/skills.go b/internal/assembly/boot/skills.go
index c060cb8ffd..df87b8f459 100644
--- a/internal/assembly/boot/skills.go
+++ b/internal/assembly/boot/skills.go
@@ -27,8 +27,8 @@ func buildSkillAssembly(opts Options, cfg *config.Config, root string, implicit
 	reuse := opts.ReuseAssembly != nil && shouldReuseDiscovery(opts.PreviousPlan) &&
 		opts.ReuseAssembly.ImplicitSkillInvocation == implicit
 	stderr := opts.Stderr
-	if reuse {
-		stderr = io.Discard
+	if opts.DiagnosticSink != nil {
+		stderr = skillDiagnosticWriter{sink: opts.DiagnosticSink}
 	}
 	a.store = skill.New(skill.Options{
 		ProjectRoot: root, ReasonixHomeDir: home, CustomPaths: cfg.SkillCustomPaths(), PluginPaths: cfg.PluginPackageSkillOwners(),
diff --git a/internal/ext/skill/discover.go b/internal/ext/skill/discover.go
index d35cee8a76..ca9f8efdf7 100644
--- a/internal/ext/skill/discover.go
+++ b/internal/ext/skill/discover.go
@@ -18,6 +18,7 @@ func (s *Store) discover(scan func(discoveryRoot) []Skill) []Skill {
 			return nil
 		}
 		current.admits = s.admits
+		current.stderr, current.said = s.stderr, s.said
 		return current.discover(current.discoverRoot)
 	}
 	var out []Skill
diff --git a/internal/frontend/cli/build_options.go b/internal/frontend/cli/build_options.go
index b438e2657b..4602685dc9 100644
--- a/internal/frontend/cli/build_options.go
+++ b/internal/frontend/cli/build_options.go
@@ -32,6 +32,7 @@ type cliBuildOverrides struct {
 	GoalTurnsUnreachable bool
 	HoldOwedChecks       bool
 	Stderr               io.Writer
+	DiagnosticSink       event.Sink
 	OnSessionRecovered   func(control.SessionRecoveryInfo) error
 	Ablation             ablation.Set
 	// NewConversation marks an interactive start that is not resuming anything, so the user's default mode applies.
@@ -82,6 +83,7 @@ func cliProfileBuildOptions(modelName string, maxStepsOverride int, requireKey b
 		StatsSource:          surface.CLI,
 		FeedbackSurface:      feedback.SurfaceTUI,
 		Stderr:               overrides.Stderr,
+		DiagnosticSink:       overrides.DiagnosticSink,
 		OnSessionRecovered:   overrides.OnSessionRecovered,
 		Ablation:             overrides.Ablation,
 		NewConversation:      overrides.NewConversation,
diff --git a/internal/frontend/cli/tui_command.go b/internal/frontend/cli/tui_command.go
index e43a75b2bb..398241d183 100644
--- a/internal/frontend/cli/tui_command.go
+++ b/internal/frontend/cli/tui_command.go
@@ -91,6 +91,7 @@ func runTUI(args []string, version string) int {
 		Version: version, WorkspaceRoot: workspaceRoot, OnSessionRecovered: cliSessionRecoveredHandler(leases),
 		Effort: f.effortOverride(), PermissionAllow: allowed, AdditionalDirs: f.addDirs,
 		NewConversation: resumePath == "",
+		DiagnosticSink:  bc,
 	})
 	if err != nil {
 		fmt.Fprintln(os.Stderr, i18n.M.ErrorPrefix, err)
diff --git a/internal/frontend/serve/hub.go b/internal/frontend/serve/hub.go
index 21541279da..3ee4b18c37 100644
--- a/internal/frontend/serve/hub.go
+++ b/internal/frontend/serve/hub.go
@@ -354,6 +354,7 @@ func (h *Hub) openBound(ctx context.Context, req OpenRequest, inherited *agentco
 			Sink:                     paneSink,
 			NativeSurfaces:           h.opts.NativeSurfaces,
 			Stderr:                   os.Stderr,
+			DiagnosticSink:           paneSink,
 			StatsSource:              h.surface(),
 			FeedbackSurface:          feedbackSurface(h.surface()),
 			AccountsURL:              accountsBaseURL(),
diff --git a/internal/frontend/serve/workspace.go b/internal/frontend/serve/workspace.go
index f683545eb7..3c14574fb7 100644
--- a/internal/frontend/serve/workspace.go
+++ b/internal/frontend/serve/workspace.go
@@ -237,6 +237,7 @@ func (s *Server) statsSurface() surface.Surface { return s.surface.Or(surface.Se
 // switch would quietly serve another project's conversations.
 func (s *Server) rebuildOptions(cur control.SessionAPI, ref string) boot.Options {
 	opts := boot.Options{Model: ref, Sink: s.rebuildSink(), NativeSurfaces: true, Stderr: os.Stderr, StatsSource: s.statsSurface(), FeedbackSurface: feedbackSurface(s.statsSurface()), AccountsURL: accountsBaseURL(), ProviderResolver: s.resolver, CleanupPendingReconciler: BackgroundCleanupReconciler}
+	opts.DiagnosticSink = s.rebuildSink()
 	if s.lastBuild != nil {
 		opts.ComputerDriver = s.lastBuild.ComputerDriver
 	}
diff --git a/release-notes/studio/unreleased/13655-renderer-safe-skill-warnings.md b/release-notes/studio/unreleased/13655-renderer-safe-skill-warnings.md
new file mode 100644
index 0000000000..ca078d6b88
--- /dev/null
+++ b/release-notes/studio/unreleased/13655-renderer-safe-skill-warnings.md
@@ -0,0 +1,4 @@
+## 修复
+
+- TUI and Studio skill diagnostics use renderer-managed notices, including first/new warnings during slash completion (#13655).
+- Identical-warning deduplication from #13656 and noninteractive stderr output remain intact.