A slot that failed ten times landed in a 30-minute cooldown and was a hard
skip for the whole window: ModelAvailable() said no, the scheduler dropped the
candidate, and the ONLY way back was a success that could never happen. In
practice an upstream that blipped for a minute — or whose quota reset in
seconds — stayed unusable for half an hour.
Cooldown is now a window with a probe gate instead of a wall:
* backoffCap 30min -> 5min. 401/403 no longer implicitly "jump to the cap"
but get an explicit authCooldown (10min); 429 keeps its 30s fixed window.
* ModelState records cooldownFrom alongside cooldownUntil, so the window has
a measurable midpoint, plus a single-token probe permit (probeInFlight).
* TryProbe() hands out that permit only in the SECOND half of the window: a
freshly failed slot stays completely silent, and past the midpoint exactly
one request may go through as a probe.
* ProbeSlots() = clamp(max_concurrent/10, 1, 2), so a source configured for
max_concurrent=10 lets exactly one request probe.
* A probe is a REAL request: success runs RecordSuccess(), which clears the
cooldown and failCount on the spot and returns the slot to full rotation.
Failure reopens the window, pushing the next probe to the NEW midpoint
instead of retrying immediately.
Quota exhaustion is modelled separately (RecordQuotaExhausted): running out of
allowance is not the upstream being broken, so it must not feed the exponential
ladder or inflate failCount. It cools until the allowance window can plausibly
have reset (capped at 30min so a manual top-up is noticed) and is recognised
from the adapter-normalized error text via ReportStatusReason.
Scheduler side: collectCands() splits a tier into normal + probe candidates
with probes strictly LAST, so probe traffic is what a tier falls back to, never
what it prefers, and the round-robin cursor rotates over the normal head only.
releaseProbes() returns every permit on all exits (success, hard failure, ctx
cancel, tier fallthrough); the 90-line inlined busy-poll loop is extracted into
pollBusyTier() to keep those exits auditable. Direct Chat/ChatStream/Image take
the same gate.
Also fixes a real blacklist bug found on the way: a slot whose pref sank to
prefMin was refused by ModelAvailable forever, long after every cooldown had
expired. Such a slot is now probeable, and one success lifts it off the floor.
Verified live against a controllable upstream (tier1 flaky, tier2 healthy):
failure ladder 5s/9s/20s/40s/79s; after healing the upstream, 10 AUTO requests
across the silent half produced ZERO upstream calls; past the midpoint a single
AUTO request produced exactly ONE upstream call, cleared the remaining 39s of
cooldown, and the next three requests were served by the recovered slot.
- adapters/opencode.lua: opencode.ai zen free pool adapter — sends the
opencode client User-Agent (zen fingerprints clients by UA; non-official
clients hit FreeUsageLimitError); pairs with api_key: public
- config: no config file ships in the repo; first run generates a default
config at the -config path with a random admin key, loopback listen and a
keyless zen source (config.EnsureDefault); remove config.example.yaml
- lua: seed bundled adapters from the embedded FS instead of a hardcoded
name list
- ui: widen model kind select (chat was clipped to 'cha')
- phase 5 bugfixes: stats ms/s bucket mixing, cleanScopes nil, ctx.Err
guards, direct-path ModelAvailable, empty stream body failure,
bestImageModel rewrite, transform failure recording, Core.mu, timer,
effective model for tool-calls
- scheduler: BuildChain sorts tiers ascending so tier 1 (highest priority) is tried first; previously descending inverted the chain (P10-1..P10-5)
- stats/api: handleStatsAPI limit→20000; CSV reads full audit via new Stats.AuditRecords (includes *.old rotation); key_names mapped by keyID() masked key; non-admin filter and keys-csv use masked keys
- server: ring buffer NewStats(10000)
- ui: dash-row card scroll area moved to table container (fix overflow below card); key view toggle (re-click same key returns to global) + kpi-exit affordance; rec-exit span
- chat: chain-failure record now surfaces first failed tier; AUTO comment sync
