[diffusion] feat: add exact component precision overrides (#36991)

docs/docs/sglang-diffusion/api/cli.mdx

@@ -131,6 +131,7 @@ pipeline's registered module name:
 | --- | --- | --- | --- |
 | Replace a component | `--component-paths.<component> {MODEL}` | `--<component>-path {MODEL}` | Load the replacement component's configuration and weights |
 | Replace only its weights | `--component-weights-paths.<component> {WEIGHTS}` | `--<component>-weights-path {WEIGHTS}` | Retain the base component configuration and replace its weights |
+| Select component precision | `--component-precisions.<component> {DTYPE}` | — | Use a loader-supported exact parameter and execution dtype |
 | Direct-load an eligible component | `--component-direct-gpu-weight-loading.<component>` | None | Use that component's audited direct-GPU loader; it must stay resident |
 | Quantize an unquantized component online | `--component-quantizations.<component> {METHOD}` | `--<component>-quantization {METHOD}` | Apply a method supported by that component's native loader |
 | Keep selected component layers unquantized | `--component-quantization-ignored-layers.<component> {PATTERN...}` | None | Pass component-local ignored-layer patterns to its online quantizer |
@@ -167,6 +168,11 @@ published, model-specific checkpoint examples; for example, all H3 sources and
 their exact overlays are kept in one
 [MiniMax-H3 compatibility table](/cookbook/diffusion/MiniMax/MiniMax-H3#checkpoint-and-adapter-formats).
 
+Exact precision overrides are capability-based. Native text and image encoders,
+standard VAE components, and native plain-state components support them;
+other component loaders reject the option instead of accepting a dtype that
+their execution stage would not honor.
+
 Direct-GPU loading is also capability-based. The existing
 `--direct-gpu-weight-loading` remains the primary DiT path. The component form
 currently supports standard native `vae` and `video_vae` state dicts on CUDA: