What causes "error building validate loop: %w" in plandex-ai/plandex?

Inspect the wrapped cause with errors.Is/errors.As on the returned error (the %w chain preserves the original)

error building validate loop: %w

Error message

error building validate loop: %w

What it means

This error wraps a real error returned by buildValidateLoop during the build race. The loop validates proposed edits and re-streams/retries; any non-cancellation error (LLM stream failure, apply error, parse error) is wrapped with %w so callers can still errors.Is against the underlying cause. context.Canceled is deliberately not reported.

Source

Thrown at app/server/model/plan/build_race.go:258

			proposedContent:      proposedContent,
			desc:                 desc,
			reasons:              reasons,
			syntaxErrors:         syntaxErrors,
			initialPhaseOnStream: onInitialStream,
			isInitial:            true,
			sessionId:            sessionId,
		})

		fileState.builderRun.AutoApplyValidationFinishedAt = time.Now()

		if err != nil {
			if errors.Is(err, context.Canceled) {
				log.Printf("Context canceled during buildValidate")
				return
			}

			log.Printf("buildRace - validation loop failed: %v", err)
			sendErr(fmt.Errorf("error building validate loop: %w", err))
		} else {
			log.Printf("buildRace - validation loop finished, valid: %v", validateResult.valid)
			if validateResult.valid {
				log.Printf("buildRace - validation loop succeeded, valid: %v", validateResult.valid)
				sendRes(raceResult{content: validateResult.updated, valid: validateResult.valid})
			} else {
				log.Printf("buildRace - validation loop failed, valid: %v", validateResult.valid)
				sendErr(fmt.Errorf("validation loop failed: %s", validateResult.problem))
			}
		}
	}()

	errs := []error{}
	errChNumReceived := 0

	for {
		select {
		case <-buildCtx.Done():

View on GitHub (pinned to e2d772072e)

Solutions

Inspect the wrapped cause with errors.Is/errors.As on the returned error (the %w chain preserves the original)
Check provider/API logs for stream failures around the AutoApplyValidationStartedAt timestamp
Retry the build; transient stream errors are common and the race may succeed on a new attempt
If persistent, fix the underlying apply/validation bug in buildValidateLoop (malformed markers, nil nodes)

Example fix

// before
if errors.Is(err, context.Canceled) { return }
log.Printf("failed: %v", err)
// after
if errors.Is(err, context.Canceled) { return }
var netErr net.Error
if errors.As(err, &netErr) && netErr.Timeout() {
    // transient - retry the build instead of surfacing to user
    return retryBuild()
}

Defensive patterns

Strategy: retry

Validate before calling

if activeBuild == nil || activeBuild.FileContent == "" {
    return fmt.Errorf("no build content to validate")
}
if buildCtx.Err() != nil {
    return buildCtx.Err() // don't start validation on a canceled context
}

Type guard

func isRetryableValidationError(err error) bool {
    return err != nil && !errors.Is(err, context.Canceled) &&
        (errors.Is(err, io.ErrUnexpectedEOF) || errors.As(err, new(net.Error)) || errors.Is(err, context.DeadlineExceeded))
}

Try / catch

res, err := fileState.buildRace(...)
if err != nil {
    if errors.Is(err, context.Canceled) {
        return nil // user canceled, expected
    }
    var wrapped error
    if errors.As(err, &wrapped) && isRetryableValidationError(wrapped) {
        return retryBuild() // transient stream failure
    }
    return fmt.Errorf("build validation failed: %w", err)
}

Prevention

Always errors.Is/errors.As the wrapped error instead of string matching
Treat context.Canceled as a no-op, never surface it as a user-facing failure
Retry transient stream errors with backoff before giving up the build
Keep validation loop steps idempotent so retries are safe

When it happens

Trigger: buildValidateLoop returns an error that is not context.Canceled — e.g. the LLM stream fails mid-validation, an edit fails to apply to the proposed content, or syntax validation returns a hard error. Triggered whenever buildRace runs its validation path (including fallback whole-file builds).

Common situations: Model/API failures during auto-apply validation, malformed edit markers the apply step cannot parse, or a context deadline exceeded that isn't the parent cancel (wrapped so it no longer matches context.Canceled/DeadlineExceeded at top level).

Related errors

AI-assisted analysis of plandex-ai/plandex@e2d772072e (2026-09-05). Data as JSON: /api/errors/e8df93fa51460ae6. Report an issue: GitHub.