Architecture

indexnow/
├── cmd/indexnow/main.go     # cobra wiring, ENV defaults, exit-code plumbing
└── internal/
    ├── cli/                 # logic in a testable form (no cobra deps)
    │   ├── submit.go        # RunSubmit, URL collection, output rendering, fail-on
    │   └── errors.go
    └── client/              # IndexNow HTTP client
        ├── client.go        # Submit / SubmitBatch, retry loop, payload marshalling
        ├── endpoints.go     # alias → URL resolution
        ├── retry.go         # backoff / jitter math
        └── errors.go

Separation of concerns

• cmd/indexnow owns cobra and OS plumbing only: flag definitions, signal handling, ENV fallbacks, mapping cli.Exit* to process exit codes.
• internal/cli owns the CLI behavior in a form that is testable without spawning a binary: RunSubmit(ctx, opts, stdin, stdout, stderr, factory) int. Inputs are read from io.Reader, output from io.Writer, the HTTP client is provided via SubmitterFactory — so tests don't need a network.
• internal/client owns the IndexNow wire format and retry policy. Concurrency-safe; configured via client.Config.

Retry policy

The client retries on HTTP 429, 5xx, and transport errors. Backoff is exponential with jitter, bounded by BaseBackoff and MaxBackoff. Retry-After is parsed as both seconds and HTTP-date. Each Result carries the final StatusCode, Attempts, the URLs in the batch, and the terminal error (if any).

Batching

SubmitBatch splits its input at MaxBatchSize = 10000 (protocol limit) and emits one Result per HTTP call, in submission order.