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package executor
import (
"context"
"fmt"
"regexp"
"strconv"
"strings"
"time"
)
var retryAfterRe = regexp.MustCompile(`(?i)retry[-_ ]after[:\s]+(\d+)`)
const maxBackoffDelay = 5 * time.Minute
// isRateLimitError returns true if err looks like a transient Claude API
// rate-limit that is worth retrying (e.g. per-minute/per-request throttle).
func isRateLimitError(err error) bool {
if err == nil {
return false
}
msg := strings.ToLower(err.Error())
return strings.Contains(msg, "rate limit") ||
strings.Contains(msg, "too many requests") ||
strings.Contains(msg, "429") ||
strings.Contains(msg, "overloaded")
}
// isQuotaExhausted returns true if err indicates the 5-hour usage quota is
// fully exhausted. Unlike transient rate limits, these should not be retried.
func isQuotaExhausted(err error) bool {
if err == nil {
return false
}
msg := strings.ToLower(err.Error())
return strings.Contains(msg, "hit your limit") ||
strings.Contains(msg, "you've hit your limit") ||
strings.Contains(msg, "you have hit your limit") ||
strings.Contains(msg, "rate limit reached (rejected)")
}
// parseRetryAfter extracts a Retry-After duration from an error message.
// Returns 0 if no retry-after value is found.
func parseRetryAfter(msg string) time.Duration {
m := retryAfterRe.FindStringSubmatch(msg)
if m == nil {
return 0
}
secs, err := strconv.Atoi(m[1])
if err != nil || secs <= 0 {
return 0
}
return time.Duration(secs) * time.Second
}
// runWithBackoff calls fn repeatedly on rate-limit errors, using exponential backoff.
// maxRetries is the max number of retry attempts (not counting the initial call).
// baseDelay is the initial backoff duration (doubled each retry).
func runWithBackoff(ctx context.Context, maxRetries int, baseDelay time.Duration, fn func() error) error {
var lastErr error
for attempt := 0; attempt <= maxRetries; attempt++ {
lastErr = fn()
if lastErr == nil {
return nil
}
if !isRateLimitError(lastErr) {
return lastErr
}
if attempt == maxRetries {
break
}
// Compute exponential backoff delay.
delay := baseDelay * (1 << attempt)
if delay > maxBackoffDelay {
delay = maxBackoffDelay
}
// Use Retry-After header value if present.
if ra := parseRetryAfter(lastErr.Error()); ra > 0 {
delay = ra
}
select {
case <-ctx.Done():
return fmt.Errorf("context cancelled during rate-limit backoff: %w", ctx.Err())
case <-time.After(delay):
}
}
return lastErr
}
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