fix(preview): default to TAESD so Wan/Kijai sampler previews actually show (main)

Port from feat. Kijai's WanVideoSampler routes Auto/Latent2RGB to core's
preview (blank for Wan latents — no rgb factors) and any other method to its
own taehv/Wan-factor previewer. Default the toggle + guard to TAESD so Wan and
core samplers both preview. Drop taew2_1/2.safetensors in models/vae_approx for
the sharp version; otherwise the Wan-factor Latent2RGB fallback still shows one.

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

Author: Code2Collapse

js/c2c_preview_toggle.js

@@ -29,22 +29,28 @@ app.registerExtension({
             id: SETTING_ID,
             name: "C2C ▸ Sampler latent preview",
             tooltip:
-                "Show the live denoising preview inside the sampler node (native " +
-                "ComfyUI preview). Auto = Latent2RGB (fast, no model). TAESD = sharper " +
-                "(needs a models/vae_approx decoder). Off = no preview.",
+                "Live denoising preview inside the sampler node — works for core " +
+                "KSampler AND Kijai WanVideoSampler. 'Wan/video-aware' uses the " +
+                "TAESD path, which routes Wan samplers to their own video previewer " +
+                "(taehv if you drop taew2_1/taew2_2.safetensors in models/vae_approx, " +
+                "otherwise a Wan-factor Latent2RGB fallback) — this is the one that " +
+                "makes Wan/Kijai previews actually appear. 'Fast' is core Latent2RGB " +
+                "(good for SD/Flux, blank for Wan). 'Off' = no preview.",
             type: "combo",
             options: [
-                { text: "Auto (Latent2RGB — fast, no model)", value: "auto" },
-                { text: "TAESD (sharper, needs vae_approx model)", value: "taesd" },
+                { text: "On — Wan/video-aware (recommended)", value: "taesd" },
+                { text: "On — fast, SD/Flux only (Latent2RGB)", value: "latent2rgb" },
                 { text: "Off", value: "off" },
             ],
-            defaultValue: "auto",
-            onChange: (v) => { applyMethod(v || "auto"); },
+            defaultValue: "taesd",
+            onChange: (v) => { applyMethod(v || "taesd"); },
         },
     ],
     async setup() {
         // Push the saved choice to the server on load so it persists across restarts.
-        const v = app.ui?.settings?.getSettingValue?.(SETTING_ID, "auto") || "auto";
+        // Default TAESD so Wan/Kijai samplers route to their own video previewer
+        // (core Auto/Latent2RGB shows nothing for Wan latents).
+        const v = app.ui?.settings?.getSettingValue?.(SETTING_ID, "taesd") || "taesd";
         applyMethod(v);
     },
 });

nodes/_c2c_preview_guard.py

@@ -56,18 +56,22 @@ def ensure_previews_enabled() -> str:
     try:
         cur = getattr(args, "preview_method", None)
         if cur == LatentPreviewMethod.NoPreviews:
-            # Prefer the module helper if present (handles its own state).
+            # Force TAESD, not Auto. TAESD is the universal method: core samplers
+            # use the taesd decoder (or fall back to Latent2RGB), and — crucially —
+            # Kijai's WanVideoSampler routes TAESD to its OWN video previewer
+            # (taehv / Wan-factor Latent2RGB), so Wan/video previews actually show.
+            # Auto resolves to core Latent2RGB, which is BLANK for Wan latents.
             try:
                 import latent_preview  # noqa: F401
                 if hasattr(latent_preview, "set_preview_method"):
-                    latent_preview.set_preview_method("auto")
+                    latent_preview.set_preview_method("taesd")
                 else:
-                    args.preview_method = LatentPreviewMethod.Auto
+                    args.preview_method = LatentPreviewMethod.TAESD
             except Exception:
-                args.preview_method = LatentPreviewMethod.Auto
-            PREVIEW_GUARD_STATUS = "forced_auto (was none)"
-            log.info("[c2c.preview] previews were OFF (--preview-method none) -> forced to Auto "
-                     "(Latent2RGB; no model, cannot fail). Set C2C_NO_FORCE_PREVIEW=1 to opt out.")
+                args.preview_method = LatentPreviewMethod.TAESD
+            PREVIEW_GUARD_STATUS = "forced_taesd (was none)"
+            log.info("[c2c.preview] previews were OFF (--preview-method none) -> forced to TAESD "
+                     "(works for core AND Kijai/Wan samplers). Set C2C_NO_FORCE_PREVIEW=1 to opt out.")
         else:
             PREVIEW_GUARD_STATUS = f"already_on ({getattr(cur, 'value', cur)})"
             log.debug("[c2c.preview] previews already enabled: %s", cur)