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fix: guard against cached context_length=0 poisoning resolution chain #231

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Merged
OmarB97 merged 1 commit into from
Jun 16, 2026
Merged

fix: guard against cached context_length=0 poisoning resolution chain #231

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22 changes: 21 additions & 1 deletion agent/model_metadata.py
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Original file line number Diff line number Diff line change
Expand Up @@ -849,6 +849,15 @@ def save_context_length(model: str, base_url: str, length: int) -> None:
Cache key is ``model@base_url`` so the same model name served from
different providers can have different limits.
"""
# Never persist non-positive values — a 0 or negative context length
# is always a bug and would poison the cache, causing downstream
# `get_model_context_length()` to return 0 (since `0 is not None`).
if length <= 0:
logger.warning(
"Refusing to cache non-positive context length %s -> %s tokens",
f"{model}@{base_url}", length,
)
return
key = f"{model}@{base_url}"
cache = _load_context_cache()
if cache.get(key) == length:
Expand Down Expand Up @@ -1591,13 +1600,24 @@ def get_model_context_length(
if base_url and provider != "lmstudio":
cached = get_cached_context_length(model, base_url)
if cached is not None:
# Reject non-positive cached values — a 0 or negative value
# is always a bug (corrupted cache, probe failure, or manual
# edit). Without this guard, `0 is not None` short-circuits
# the resolution chain and the compressor gets context_length=0,
# breaking every status-bar and /usage display downstream.
if cached <= 0:
logger.warning(
"Dropping non-positive cache entry %s@%s -> %s; re-resolving",
model, base_url, cached,
)
_invalidate_cached_context_length(model, base_url)
# Invalidate stale Codex OAuth cache entries: pre-PR #14935 builds
# resolved gpt-5.x to the direct-API value (e.g. 1.05M) via
# models.dev and persisted it. Codex OAuth caps at 272K for every
# slug, so any cached Codex entry at or above 400K is a leftover
# from the old resolution path. Drop it and fall through to the
# live /models probe in step 5 below.
if provider == "openai-codex" and cached >= 400_000:
elif provider == "openai-codex" and cached >= 400_000:
logger.info(
"Dropping stale Codex cache entry %s@%s -> %s (pre-fix value); "
"re-resolving via live /models probe",
Expand Down
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