feat: wire SSE routes through typelate/sse with --wire-typelate-sse

[crhntr]

Implements the first --wire-* flag from decision 00007: --wire-typelate-sse generates SSE handlers that wire the protocol through github.com/typelate/sse instead of generating it.

With the flag, the handler calls sse.New(response, request, http.StatusOK) — which owns the stream headers, flushing, and goroutine safety — so the generated http.Flusher assertion, header block, and sync.Mutex disappear, and SSETemplateData loses its WriteTo wire writer. Each render callback maps the template-set metadata to options (.ID → sse.WithID, .Event → sse.WithEvent, .Retry → sse.WithRetry) and sends the rendered frame with stream.Message.

Render callbacks may declare a variadic option parameter:

func (Server) Numbers(_ context.Context, sseNum func(int, ...sse.MessageOption) error) error {
	return sseNum(7, sse.WithID("n7"))
}

Resolution accepts func(T, ...O) error and records the option element type; generation validates O is the wired library's MessageOption and the closure forwards the options to Message (receiver options are appended after the template-derived ones, so they win). An options parameter without the flag, a wrong option type, and the not-yet-supported --output-datastar combination are each rejected with byte-exact err_* goldens.

The reference txtar go gets the module, generates, checks, and executes both routes against a live mux, asserting the frames — including the forwarded id: n7.

🤖 Generated with Claude Code

https://claude.ai/code/session_018Phdz9o5BUZMnd643Am5Ef

[Copilot]

🟡 Changes recommended

There are a couple of user-facing validation/error-path issues (misleading “too many params” SSE callback message; overly strict option-type check rejecting aliases) that should be corrected before merging.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds a new generation mode for SSE routes where Muxt delegates SSE stream wiring to github.com/typelate/sse via a new --wire-typelate-sse flag, enabling cleaner generated handlers and optional forwarding of variadic message options through render callbacks.

Changes:

• Introduces --wire-typelate-sse (CLI/config/docs) and prevents combining it with --output-datastar.
• Extends callback-shape resolution to recognize func(T, ...O) error and validates O against sse.MessageOption during SSE generation.
• Updates SSE handler/codegen to call sse.New(...) and send frames via stream.Message(...), and adds reference/error goldens for the new behavior.

File summaries

File	Description
internal/muxt/call.go	Records variadic callback option element types and allows func(T, ...O) error callback shapes.
internal/generate/sse.go	Wires SSE generation through typelate/sse when enabled; validates callback options type and forwards options into stream.Message.
internal/generate/sse_template_data.go	Omits generating SSETemplateData.WriteTo under --wire-typelate-sse.
internal/generate/routes.go	Adds WireTypelateSSE to generator configuration.
internal/generate/html.go	Rejects callback options on non-SSE (HTML) execute callbacks.
internal/cli/commands.go	Adds --wire-typelate-sse flag, config-to-args plumbing, and rejects --wire-typelate-sse with --output-datastar.
docs/reference/commands/generate.md	Documents the new --wire-typelate-sse flag and its behavioral implications.
cmd/muxt/testdata/reference_wire_typelate_sse.txt	End-to-end reference test that go-gets typelate/sse, generates, and asserts streamed frames (including forwarded id).
cmd/muxt/testdata/err_wire_typelate_sse_with_datastar.txt	Golden asserting the mutual-exclusion error for --wire-typelate-sse + --output-datastar.
cmd/muxt/testdata/err_callback_options_wrong_type.txt	Golden asserting callback option type must be ...sse.MessageOption.
cmd/muxt/testdata/err_callback_options_without_wire.txt	Golden asserting callback options require --wire-typelate-sse.

Review details

• Files reviewed: 11/11 changed files
• Comments generated: 2
• Review effort level: Lite

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