Addresses review feedback from rumpl and simonferquel on PR #2096.
The previous approach extracted Retry-After metadata in a dispatcher function
that type-switched on provider SDK error types (`*anthropic.Error`,
`*openai.Error`). This kept all providers coupled to the modelerrors package
and duplicated parsing logic.
New design:
1. `modelerrors.StatusError` — a thin typed wrapper carrying:
- StatusCode int
- RetryAfter time.Duration (parsed from Retry-After header)
- Err error (original SDK error, accessible via Unwrap)
2. `modelerrors.WrapHTTPError(statusCode, resp, err)` — wraps any provider
error in StatusError; parses Retry-After from resp.Header if non-nil.
3. `modelerrors.ParseRetryAfterHeader(value)` — shared RFC 7231 §7.1.3
parser (integer seconds + HTTP-date). No SDK imports.
4. `modelerrors.ClassifyModelError(err)` — single-arg; uses errors.As to
find *StatusError in the chain; falls back to message/pattern matching for
providers not yet wrapped (e.g. Bedrock).
5. Three new wrap.go files (one per provider family), each a single function:
- pkg/model/provider/anthropic/wrap.go — wrapAnthropicError(*anthropic.Error)
- pkg/model/provider/oaistream/wrap.go — WrapOpenAIError(*openai.Error) (exported)
- pkg/model/provider/gemini/wrap.go — wrapGeminiError(*genai.APIError)
6. Wrap sites — one-line change at Recv() in each adapter:
- anthropic/adapter.go, beta_adapter.go
- oaistream/adapter.go
- openai/response_stream.go (reuses oaistream.WrapOpenAIError)
- gemini/adapter.go
No changes to fallback.go logic — ClassifyModelError signature stays
`(err error)` and retry/rate-limit decisions are unchanged.
Assisted-By: docker-agent
When a model returns HTTP 429 (Too Many Requests):
- If fallback models are configured: skip to next fallback immediately (existing behavior preserved)
- If no fallbacks are configured: retry the same model using the Retry-After header duration (capped at 60s), falling back to exponential backoff if the header is absent
HTTP 500 was already handled as retryable via IsRetryableStatusCode — no change needed.
New additions to pkg/modelerrors:
- ExtractRetryAfter(err): extracts Retry-After duration from *anthropic.Error and *openai.Error responses
- parseRetryAfterHeader(value): parses integer-seconds or HTTP-date Retry-After values
- ClassifyModelError(err): unified classifier returning (retryable, rateLimited bool, retryAfter time.Duration)
- MaxRetryAfterWait constant (60s cap)
pkg/runtime/fallback.go changes:
- Replace both IsRetryableModelError call sites with ClassifyModelError
- Add handleModelError helper to avoid duplicating classification logic
- 429 with fallbacks → break to next model (unchanged behavior)
- 429 without fallbacks → sleep(min(retryAfter, 60s) or backoff), then continue
Fixes#2095
Assisted-By: docker-agent
Break up the oversized runtime.go (2510 lines) by extracting cohesive
groups of functions into dedicated files, and move pure error
classification utilities into a new reusable package.
New files in pkg/runtime:
- model_picker.go: model change/revert tool handlers
- agent_delegation.go: sub-agent dispatch, task transfer, handoffs
New package pkg/modelerrors:
- ContextOverflowError type and detection
- HTTP status code extraction (Anthropic, Gemini, OpenAI)
- Retryable error classification
- Exponential backoff with jitter
- User-friendly error formatting
Assisted-By: docker-agent
Go Expert Coding agent
David Gageot