fix: activate fallback provider on repeated empty responses + user-visible status (#7505)

When models return empty responses (no content, no tool calls, no
reasoning), Hermes previously retried 3 times silently then fell through
to '(empty)' — without ever trying the fallback provider chain. Users on
GLM-4.5-Air and similar models experienced what appeared to be a
complete hang, especially in gateway (Telegram/Discord) contexts where
the silent retries produced zero feedback.

Changes:
- After exhausting 3 empty retries, attempt _try_activate_fallback()
  before giving up with '(empty)'. If fallback succeeds, reset retry
  counter and continue the conversation loop with the new provider.
- Replace all _vprint() calls in recovery paths with _emit_status(),
  which surfaces messages through both CLI (_vprint with force=True)
  and gateway (status_callback -> adapter.send). Users now see:
  * '⚠️ Empty response from model — retrying (N/3)' during retries
  * '⚠️ Model returning empty responses — switching to fallback...'
  * '↻ Switched to fallback: <model> (<provider>)' on success
  * ' Model returned no content after all retries [and fallback]'
- Add logger.warning() throughout empty response paths for log file
  visibility (model name, provider, retry counts).
- Upgrade _last_content_with_tools fallback from logger.debug to
  logger.info + _emit_status so recovery is visible.
- Upgrade thinking-only prefill continuation to use _emit_status.

Tests:
- test_empty_response_triggers_fallback_provider: verifies fallback
  activation after 3 empty retries produces content from fallback model
- test_empty_response_fallback_also_empty_returns_empty: verifies
  graceful degradation when fallback also returns empty
- test_empty_response_emits_status_for_gateway: verifies _emit_status
  is called during retries so gateway users see feedback

Addresses #7180.
This commit is contained in:
Teknium
2026-04-10 19:15:41 -07:00
committed by GitHub
parent 992422910c
commit 842e669a13
2 changed files with 178 additions and 15 deletions

View File

@@ -9459,7 +9459,8 @@ class AIAgent:
fallback = getattr(self, '_last_content_with_tools', None)
if fallback:
_turn_exit_reason = "fallback_prior_turn_content"
logger.debug("Empty follow-up after tool calls — using prior turn content as final response")
logger.info("Empty follow-up after tool calls — using prior turn content as final response")
self._emit_status("↻ Empty response after tool calls — using earlier content as final answer")
self._last_content_with_tools = None
self._empty_content_retries = 0
for i in range(len(messages) - 1, -1, -1):
@@ -9490,9 +9491,13 @@ class AIAgent:
)
if _has_structured and self._thinking_prefill_retries < 2:
self._thinking_prefill_retries += 1
self._vprint(
f"{self.log_prefix}Thinking-only response — "
f"prefilling to continue "
logger.info(
"Thinking-only response (no visible content)"
"prefilling to continue (%d/2)",
self._thinking_prefill_retries,
)
self._emit_status(
f"↻ Thinking-only response — prefilling to continue "
f"({self._thinking_prefill_retries}/2)"
)
interim_msg = self._build_assistant_message(
@@ -9508,23 +9513,57 @@ class AIAgent:
# Model returned nothing — no content, no
# structured reasoning, no tool calls. Common
# with open models (transient provider issues,
# rate limits, sampling flukes). Silently retry
# up to 3 times before giving up. Skip when
# rate limits, sampling flukes). Retry up to 3
# times before attempting fallback. Skip when
# content has inline <think> tags (model chose
# to reason, just no visible text).
_truly_empty = not final_response.strip()
if _truly_empty and not _has_structured and self._empty_content_retries < 3:
self._empty_content_retries += 1
self._vprint(
f"{self.log_prefix}Empty response (no content or reasoning) "
f"retrying ({self._empty_content_retries}/3)",
force=True,
logger.warning(
"Empty response (no content or reasoning) "
"retry %d/3 (model=%s)",
self._empty_content_retries, self.model,
)
self._emit_status(
f"⚠️ Empty response from model — retrying "
f"({self._empty_content_retries}/3)"
)
continue
# Exhausted prefill attempts, empty retries, or
# structured reasoning with no content —
# fall through to "(empty)" terminal.
# ── Exhausted retries — try fallback provider ──
# Before giving up with "(empty)", attempt to
# switch to the next provider in the fallback
# chain. This covers the case where a model
# (e.g. GLM-4.5-Air) consistently returns empty
# due to context degradation or provider issues.
if _truly_empty and self._fallback_chain:
logger.warning(
"Empty response after %d retries — "
"attempting fallback (model=%s, provider=%s)",
self._empty_content_retries, self.model,
self.provider,
)
self._emit_status(
"⚠️ Model returning empty responses — "
"switching to fallback provider..."
)
if self._try_activate_fallback():
self._empty_content_retries = 0
self._emit_status(
f"↻ Switched to fallback: {self.model} "
f"({self.provider})"
)
logger.info(
"Fallback activated after empty responses: "
"now using %s on %s",
self.model, self.provider,
)
continue
# Exhausted retries and fallback chain (or no
# fallback configured). Fall through to the
# "(empty)" terminal.
_turn_exit_reason = "empty_response_exhausted"
reasoning_text = self._extract_reasoning(assistant_message)
assistant_msg = self._build_assistant_message(assistant_message, finish_reason)
@@ -9533,9 +9572,28 @@ class AIAgent:
if reasoning_text:
reasoning_preview = reasoning_text[:500] + "..." if len(reasoning_text) > 500 else reasoning_text
self._vprint(f"{self.log_prefix} Reasoning-only response (no visible content). Reasoning: {reasoning_preview}")
logger.warning(
"Reasoning-only response (no visible content) "
"after exhausting retries and fallback. "
"Reasoning: %s", reasoning_preview,
)
self._emit_status(
"⚠️ Model produced reasoning but no visible "
"response after all retries. Returning empty."
)
else:
self._vprint(f"{self.log_prefix} Empty response (no content or reasoning) after 3 retries.")
logger.warning(
"Empty response (no content or reasoning) "
"after %d retries. No fallback available. "
"model=%s provider=%s",
self._empty_content_retries, self.model,
self.provider,
)
self._emit_status(
"❌ Model returned no content after all retries"
+ (" and fallback attempts." if self._fallback_chain else
". No fallback providers configured.")
)
final_response = "(empty)"
break