GitLab

refactor(channel): split long functions, extract shared validation, move billing validation to service

- Split Update (98→25 lines), buildCache (54→20 lines), Create (51→25 lines)
  into focused sub-functions: applyUpdateInput, checkGroupConflicts,
  fetchChannelData, populateChannelCache, storeErrorCache, getOldGroupIDs,
  invalidateAuthCacheForGroups
- Extract validateChannelConfig to eliminate duplicated validation calls
  between Create and Update
- Move validatePricingBillingMode from handler to service layer for
  proper separation of concerns
- Add error logging to IsModelRestricted (was silently swallowing errors)
- Add 12 new tests: ToUsageFields, billing mode validation, antigravity
  wildcard mapping isolation, Create/Update mapping conflict integration

Antigravity groups were incorrectly matching pricing and model mapping
entries from anthropic/gemini platform tabs. Each platform should be
strictly isolated — antigravity groups only use antigravity-tagged pricing.

- GetGroupPlatforms failure now stores error-TTL cache and returns error (fail-close)
- Frontend group-to-channel conflict map loads all channels instead of current page only
- Toggle channel status reloads list when active filter would hide the changed item

P0-1: Credits degraded response retry + fail-open
- Add isAntigravityDegradedResponse() to detect transient API failures
- Retry up to 3 times with exponential backoff (500ms/1s/2s)
- Invalidate singleflight cache between retries
- Fail-open after exhausting retries instead of 5h circuit break

P1-1: Fix channel restriction pre-check timing conflict
- Swap checkClaudeCodeRestriction before checkChannelPricingRestriction
- Ensures channel restriction is checked against final fallback groupID

P1-2: Add interval pricing validation (frontend + backend)
- Backend: ValidateIntervals() with boundary, price, overlap checks
- Frontend: validateIntervals() with Chinese error messages
- Rules: MinTokens>=0, MaxTokens>MinTokens, prices>=0, no overlap

P2: Fix cross-platform same-model pricing/mapping override
- Store cache keys using original platform instead of group platform
- Lookup across matching platforms (antigravity→anthropic→gemini)
- Prevents anthropic/gemini same-name models from overwriting each other

Move the model pricing restriction check from 8 handler entry points
to the account scheduling phase (SelectAccountForModelWithExclusions /
SelectAccountWithLoadAwareness), aligning restriction with billing:

- requested: check original request model against pricing list
- channel_mapped: check channel-mapped model against pricing list
- upstream: per-account check using account-mapped model

Handler layer now only resolves channel mapping (no restriction).
Scheduling layer performs pre-check for requested/channel_mapped,
and per-account filtering for upstream billing source.

- TestIsPlatformPricingMatch: 12 cases covering all platform combinations
- TestMatchingPlatforms: 4 cases for platform expansion
- TestGetChannelModelPricing_AntigravityCrossPlatform: antigravity sees anthropic pricing
- TestGetChannelModelPricing_AnthropicCannotSeeAntigravityPricing: no reverse leakage
- TestResolveChannelMapping_AntigravityCrossPlatform: antigravity uses anthropic mapping
- TestFilterValidIntervals: 8 cases for empty interval filtering
- TestHasEnoughCredits: 10 cases for credits balance threshold logic
- Extract hasEnoughCredits() pure function for testability

- Parse candidatesTokensDetails from Gemini API to separate image/text output tokens
- Add image_output_tokens and image_output_cost to usage_log (migration 089)
- Support per-image-token pricing via output_cost_per_image_token from model pricing data
- Channel pricing ImageOutputPrice override works in token billing mode
- Auto-fill image_output_price in channel pricing form from model defaults
- Add "channel_mapped" billing model source as new default (migration 088)
- Bills by model name after channel mapping, before account mapping
- Fix channel cache error TTL sign error (115s → 5s)
- Fix Update channel only invalidating new groups, not removed groups
- Fix frontend model_mapping clearing sending undefined instead of {}
- Credits balance precheck via shared AccountUsageService cache before injection
- Skip credits injection for accounts with insufficient balance
- Don't mark credits exhausted for "exhausted your capacity on this model" 429s

- 渠道模型映射：支持精确匹配和通配符映射，按平台隔离
- 渠道模型定价：支持 token/按次/图片三种计费模式，区间分层定价
- 模型限制：渠道可限制仅允许定价列表中的模型
- 计费模型来源：支持 requested/upstream 两种计费模型选择
- 用量统计：usage_logs 新增 channel_id/model_mapping_chain/billing_tier/billing_mode 字段
- Dashboard 支持 model_source 维度（requested/upstream/mapping）查看模型统计
- 全部 gateway handler 统一接入 ResolveChannelMappingAndRestrict
- 修复测试：同步 SoraGenerationRepository 接口、SQL INSERT 参数、scan 字段