Files
chat/chat/services/skip_narration.py
T

133 lines
4.5 KiB
Python

"""Skip narration service (T53).
Generates brief transition prose for elision and jump skips.
Skips come in two flavors that read very differently:
* **Elision** — collapses an in-progress activity into its expected
end-state in 1-2 sentences, narrated from the speaker bot's POV.
Example: "skip ahead to when we arrive" while the characters are
driving — output describes pulling into the lot.
* **Jump** — bridges a longer fiction-time delta ("next morning", "a
week later") in 2-3 sentences, setting the scene at the new time.
Output is free-form prose, not structured JSON, so this service calls
``client.generate`` directly rather than going through the classifier
path used by, e.g., :mod:`chat.services.scene_summarize`. A
deterministic template fallback fires on any LLM failure so the skip
flow keeps moving even when the model is down — important because
skips are a UI-blocking operation; we'd rather show a parenthetical
sentence than hang the chat indefinitely.
"""
from __future__ import annotations
from chat.llm.client import LLMClient, Message
_ELISION_SYSTEM = (
"You write a brief 1-2 sentence transition that elides the time "
"between an in-progress activity and its expected end-state, "
"narrated from the speaker's POV. Keep it grounded and concrete. "
"Do not invent new events or characters."
)
_JUMP_SYSTEM = (
"You write a brief 2-3 sentence transition narrating a jump in "
"fiction time (e.g., 'next morning', 'a week later'), narrated "
"from the speaker's POV. Set the scene at the new time. Keep it "
"grounded — no invented major events. If a landing-state hint is "
"provided, weave it in naturally."
)
async def narrate_skip(
client: LLMClient,
*,
narrative_model: str,
skip_kind: str,
speaker_bot: dict,
you_name: str,
current_time: str,
new_time: str,
current_activity: str,
landing_state_hint: str = "",
timeout_s: float = 60.0,
) -> str:
"""Generate brief transition prose for a time skip.
``skip_kind`` is ``"elision"`` or ``"jump"``; any other value short-
circuits to the deterministic fallback (defensive — callers
shouldn't be inventing new kinds without updating this service).
Returns plain text. Never raises: any LLM error, an empty/blank
result, or an unknown ``skip_kind`` falls back to a parenthetical
template like ``"(next morning: having coffee in the kitchen.)"``
so the skip UI always has *something* to render.
"""
fallback = _build_fallback(
skip_kind=skip_kind,
new_time=new_time,
current_activity=current_activity,
landing_state_hint=landing_state_hint,
)
if skip_kind not in ("elision", "jump"):
return fallback
system = _ELISION_SYSTEM if skip_kind == "elision" else _JUMP_SYSTEM
user = (
f"Speaker: {speaker_bot.get('name', 'speaker')}\n"
f"Persona: {speaker_bot.get('persona', '')}\n"
f"Other party: {you_name}\n"
f"Current time: {current_time}\n"
f"New time: {new_time}\n"
f"Current activity: {current_activity}\n"
)
if landing_state_hint:
user += f"Landing state hint: {landing_state_hint}\n"
try:
result = await client.generate(
[
Message(role="system", content=system),
Message(role="user", content=user),
],
model=narrative_model,
max_tokens=200,
temperature=0.7,
timeout_s=timeout_s,
)
text = (result or "").strip()
if not text:
return fallback
return text
except Exception:
# Any failure — network blip, timeout, mock raising in tests —
# collapses to the deterministic template so the skip pipeline
# is never blocked on the LLM being available.
return fallback
def _build_fallback(
*,
skip_kind: str,
new_time: str,
current_activity: str,
landing_state_hint: str,
) -> str:
"""Deterministic parenthetical narration used when the LLM fails.
Both flavors render the same shape today: ``(<new_time>:
<detail>.)``. They're separated as branches to make it easy to
diverge later (e.g. an elision-specific template) without churning
the call site or the public signature.
"""
detail = landing_state_hint or current_activity or "moments later"
if skip_kind == "elision":
return f"({new_time}: {detail}.)"
return f"({new_time}: {detail}.)"
__all__ = ["narrate_skip"]