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Python

"""Local, catalog-aware prompt enhancement handler."""
from __future__ import annotations
import logging
import os
import random
import uuid
from threading import RLock
from typing import TYPE_CHECKING
from _routes._errors import HTTPError
from api_types import EnhancePromptRequest, EnhancePromptResponse, IcLoraCatalogItem, LoraCatalogItem
from handlers.base import StateHandlerBase
from handlers.generation_handler import GenerationHandler
from handlers.pipelines_handler import PipelinesHandler
from handlers.text_handler import TextHandler
from server_utils.media_validation import normalize_optional_path, validate_image_file
from services.gemini_text_client import resolve_gemini_model
from services.interfaces import PromptEnhancerPipeline
from services.lora_catalog import LoraCatalogProvider
from services.prompt_enhancement import (
build_audio_visual_caption_system_prompt,
build_conditioning_system_prompt,
build_ic_lora_enhancement_system_prompt,
build_image_edit_system_prompt,
build_image_generation_system_prompt,
build_keyframe_enhancement_system_prompt,
build_lora_enhancement_system_prompt,
build_template_fill_system_prompt,
enforce_trigger_placements,
fill_prompt_template,
parse_template_fill_response,
)
from services.prompt_enhancement.i2v_frames import KeyframeStill
from services.prompt_enhancer_pipeline.gemini_prompt_enhancer_pipeline import GeminiPromptEnhancerPipeline
from services.services_utils import get_device_type
from state.app_state_types import AppState
logger = logging.getLogger(__name__)
if TYPE_CHECKING:
from runtime_config.runtime_config import RuntimeConfig
# Deliberately independent of StateHandlerBase._resolve_seed(): that helper honors the app's
# reproducibility seed lock (and a fixed constant in dev mode), which would make every enhance
# call — including a redo — produce the exact same output. Enhancement is a quick, exploratory
# action where a fresh draw each call is the whole point.
_MAX_ENHANCE_SEED = 2147483647
class PromptEnhancementHandler(StateHandlerBase):
def __init__(
self,
state: AppState,
lock: RLock,
generation_handler: GenerationHandler,
pipelines_handler: PipelinesHandler,
text_handler: TextHandler,
lora_catalog_provider: LoraCatalogProvider,
prompt_enhancer_pipeline_class: type[PromptEnhancerPipeline],
gemini_pipeline: GeminiPromptEnhancerPipeline,
config: RuntimeConfig,
) -> None:
super().__init__(state, lock, config)
self._generation = generation_handler
self._pipelines = pipelines_handler
self._text_handler = text_handler
self._lora_catalog_provider = lora_catalog_provider
self._prompt_enhancer_pipeline_class = prompt_enhancer_pipeline_class
self._gemini_pipeline = gemini_pipeline
def _random_seed(self) -> int:
return random.randint(0, _MAX_ENHANCE_SEED)
def enhance(self, req: EnhancePromptRequest) -> EnhancePromptResponse:
# Enhance never occupies the GPU slot (see PipelinesHandler.
# evict_gpu_pipeline_for_prompt_enhancement) but still needs to mutually exclude with
# generation and with itself — an abandoned/orphaned enhance call (e.g. the tab reloaded
# mid-request) must not race a Generate click, a second Enhance click, or a generation
# that's still loading its pipeline (reserved_generation_start covers that window; a bare
# is_generation_running() check does not — see its own docstring). The "api" generation
# slot gives us the mutual exclusion for free: it's the same bookkeeping every other
# handler already does, and it doesn't require gpu_slot to be set.
with self._generation.reserved_generation_start():
gemma_root: str | None = None
if req.provider == "local":
gemma_root = self._text_handler.resolve_prompt_enhancer_root_if_downloaded()
if gemma_root is None:
raise HTTPError(409, "LOCAL_TEXT_ENCODER_NOT_AVAILABLE")
elif not self.state.app_settings.gemini_api_key:
raise HTTPError(400, "GEMINI_API_KEY_MISSING")
generation_id = uuid.uuid4().hex[:8]
self._generation.start_api_generation(generation_id)
try:
enhanced = self._resolve_and_enhance(req, gemma_root)
except HTTPError as e:
self._generation.fail_generation(e.detail)
raise
except Exception as e:
self._generation.fail_generation(str(e))
raise HTTPError(500, str(e)) from e
self._generation.complete_generation(enhanced)
return EnhancePromptResponse(enhancedPrompt=enhanced)
def _resolve_and_enhance(self, req: EnhancePromptRequest, gemma_root: str | None) -> str:
if req.mediaType == "image":
# No catalog LoRA concept for images (validated at the request level) — always an
# explicit, image-domain system prompt, never the video-oriented generic fallback.
system_prompt = (
build_image_edit_system_prompt() if req.imagePath is not None
else build_image_generation_system_prompt()
)
return self._run_free_rewrite(req, system_prompt, gemma_root)
if req.icLoraId is not None:
ic_lora = self._lora_catalog_provider.get_ic_lora(req.icLoraId)
if ic_lora is None:
raise HTTPError(404, "LORA_CATALOG_ID_NOT_FOUND")
return self._enhance_ic_lora(ic_lora, req, gemma_root)
if req.loraCatalogIds:
loras: list[LoraCatalogItem] = []
for catalog_id in req.loraCatalogIds:
lora = self._lora_catalog_provider.get_lora(catalog_id)
if lora is None:
raise HTTPError(404, "LORA_CATALOG_ID_NOT_FOUND")
loras.append(lora)
return self._enhance_loras(loras, req, gemma_root)
if req.conditioningType is not None:
system_prompt = build_conditioning_system_prompt(req.conditioningType)
return self._run_free_rewrite(req, system_prompt, gemma_root)
return self._run_free_rewrite(req, self._default_video_system_prompt(req), gemma_root)
def _default_video_system_prompt(self, req: EnhancePromptRequest) -> str | None:
if req.keyframes:
return self._keyframe_system_prompt()
return self._video_system_prompt(t2v=req.imagePath is None)
def _keyframe_system_prompt(self) -> str:
spec = self._text_handler.active_ltx_model_spec()
audio_visual = spec is not None and spec.wants_audio_visual_captions
return build_keyframe_enhancement_system_prompt(audio_visual=audio_visual)
def _video_system_prompt(self, *, t2v: bool) -> str | None:
"""The active model's own caption style, or None to keep each provider's default.
Only the audio-visual generations (2.5) need this: their captions cover the soundscape,
which neither the generic Gemini fallback nor a 2.3-era prompt asks for.
"""
spec = self._text_handler.active_ltx_model_spec()
if spec is None or not spec.wants_audio_visual_captions:
return None
return build_audio_visual_caption_system_prompt(t2v=t2v)
def enhance_for_generation(
self,
prompt: str,
*,
image_path: str | None,
last_image_path: str | None = None,
keyframes: list[KeyframeStill] | None = None,
duration: int | None = None,
fps: int | None = None,
) -> str:
"""Rewrite ``prompt`` on the local enhancer for a generation that's already started.
Only for the local text-encoding path: API encoding enhances server-side inside the
same call, so it never gets here. Deliberately not `enhance()` — the caller already
holds the generation slot, and there's no provider choice to make, only "is the
enhancer on disk".
Never raises: enhancement is a quality step, so a missing checkpoint or a failed
rewrite degrades to the prompt as typed rather than failing the generation.
"""
if not prompt.strip():
return prompt
gemma_root = self._text_handler.resolve_prompt_enhancer_root_if_downloaded()
if gemma_root is None:
logger.info("Skipping automatic enhancement: no local prompt enhancer downloaded")
return prompt
try:
pipeline = self._load_prompt_enhancer_pipeline(gemma_root)
system_prompt = (
self._keyframe_system_prompt()
if keyframes
else self._video_system_prompt(t2v=image_path is None)
)
seed = self._random_seed()
if image_path is not None or keyframes:
first_path = image_path or (keyframes[0][0] if keyframes else None)
assert first_path is not None
enhanced = pipeline.enhance_i2v(
prompt,
first_path,
system_prompt=system_prompt,
seed=seed,
last_image_path=None if keyframes else last_image_path,
keyframes=keyframes,
duration=duration,
fps=fps,
)
else:
enhanced = pipeline.enhance_t2v(prompt, system_prompt=system_prompt, seed=seed)
except Exception:
logger.warning("Automatic local enhancement failed; using the prompt as typed", exc_info=True)
return prompt
if not enhanced.strip():
return prompt
logger.info(
"Enhanced prompt locally for generation (%d -> %d chars): %s",
len(prompt),
len(enhanced),
enhanced,
)
return enhanced
def _enhance_loras(
self, loras: list[LoraCatalogItem], req: EnhancePromptRequest, gemma_root: str | None
) -> str:
# None of the plain LoRAs in the catalog have a prompt_template today (only IC-LoRAs
# do) — the multi-select path is always a free rewrite.
system_prompt = build_lora_enhancement_system_prompt(loras)
enhanced = self._run_free_rewrite(req, system_prompt, gemma_root)
return enforce_trigger_placements(enhanced, loras)
def _enhance_ic_lora(
self, ic_lora: IcLoraCatalogItem, req: EnhancePromptRequest, gemma_root: str | None
) -> str:
if ic_lora.prompt_template is not None:
return self._run_template_fill(ic_lora, req, gemma_root)
system_prompt = build_ic_lora_enhancement_system_prompt(ic_lora)
enhanced = self._run_free_rewrite(req, system_prompt, gemma_root)
return enforce_trigger_placements(enhanced, [ic_lora])
def _run_free_rewrite(
self, req: EnhancePromptRequest, system_prompt: str | None, gemma_root: str | None
) -> str:
# Reject an invalid/unreadable/oversized path before it reaches either provider — the
# API path in particular would otherwise base64-encode and ship arbitrary file bytes to
# a third-party API with no gate at all.
keyframes = self._validated_keyframes(req)
image_path = (
None if keyframes else normalize_optional_path(req.imagePath)
)
last_image_path = (
None
if req.mediaType == "image" or keyframes
else normalize_optional_path(req.lastImagePath)
)
if image_path is not None:
validate_image_file(image_path)
if last_image_path is not None:
validate_image_file(last_image_path)
seed = self._random_seed()
first_path = image_path or (keyframes[0][0] if keyframes else None)
if req.provider == "api":
resolved_model = resolve_gemini_model(self.state.app_settings.gemini_model)
logger.info("Enhancing prompt via Gemini API (%s)", resolved_model)
api_key = self.state.app_settings.gemini_api_key
if first_path is not None:
return self._gemini_pipeline.enhance_i2v(
req.prompt,
first_path,
system_prompt=system_prompt,
seed=seed,
api_key=api_key,
model=resolved_model,
last_image_path=last_image_path,
keyframes=keyframes,
duration=req.duration,
fps=req.fps,
)
return self._gemini_pipeline.enhance_t2v(
req.prompt,
system_prompt=system_prompt,
seed=seed,
api_key=api_key,
model=resolved_model,
)
logger.info("Enhancing prompt via local Gemma")
assert gemma_root is not None
pipeline = self._load_prompt_enhancer_pipeline(gemma_root)
if first_path is not None:
return pipeline.enhance_i2v(
req.prompt,
first_path,
system_prompt=system_prompt,
seed=seed,
last_image_path=last_image_path,
keyframes=keyframes,
duration=req.duration,
fps=req.fps,
)
return pipeline.enhance_t2v(req.prompt, system_prompt=system_prompt, seed=seed)
def _validated_keyframes(self, req: EnhancePromptRequest) -> list[KeyframeStill] | None:
if req.mediaType == "image" or not req.keyframes:
return None
frames: list[KeyframeStill] = []
for keyframe in req.keyframes:
path = normalize_optional_path(keyframe.imagePath)
if path is None:
raise HTTPError(400, "Each keyframe requires an image path")
validate_image_file(path)
frames.append((path, keyframe.frameIndex, keyframe.strength))
frames.sort(key=lambda item: item[1])
return frames
def _run_template_fill(
self, ic_lora: IcLoraCatalogItem, req: EnhancePromptRequest, gemma_root: str | None
) -> str:
# req.imagePath is intentionally unused here — template fill is always a text-only
# enhance_t2v call (the fixed template scaffold carries no reference-image slot), unlike
# the free-rewrite IC-LoRA path below it, which does route an image through enhance_i2v.
assert ic_lora.prompt_template is not None
system_prompt = build_template_fill_system_prompt(ic_lora)
seed = self._random_seed()
try:
if req.provider == "api":
resolved_model = resolve_gemini_model(self.state.app_settings.gemini_model)
logger.info("Enhancing prompt via Gemini API (%s)", resolved_model)
raw = self._gemini_pipeline.enhance_t2v(
req.prompt,
system_prompt=system_prompt,
seed=seed,
api_key=self.state.app_settings.gemini_api_key,
model=resolved_model,
)
else:
logger.info("Enhancing prompt via local Gemma")
assert gemma_root is not None
pipeline = self._load_prompt_enhancer_pipeline(gemma_root)
raw = pipeline.enhance_t2v(req.prompt, system_prompt=system_prompt, seed=seed)
values = parse_template_fill_response(raw, set(ic_lora.prompt_template.placeholders))
return fill_prompt_template(ic_lora.prompt_template, values)
except ValueError as e:
raise HTTPError(500, f"PROMPT_TEMPLATE_FILL_FAILED: {e}") from e
def _load_prompt_enhancer_pipeline(self, gemma_root: str) -> PromptEnhancerPipeline:
self._pipelines.evict_gpu_pipeline_for_prompt_enhancement()
device = os.getenv("LTX_PROMPT_ENHANCER_DEVICE", "").strip()
if not device:
device = get_device_type(self.config.device)
logger.info("Loading local prompt enhancer on %s", device)
return self._prompt_enhancer_pipeline_class.create(gemma_root, device)