feat(dap): custom-request extension point for host debug requests#417
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dap.Server.dispatch was a closed command switch — unknown requests hit the default case and returned "not implemented", with no way for a hosting process to serve its own debug requests over the DAP connection. Add AttachConfig.CustomRequestHandler, invoked from dispatch's fallback path under the CPU lock so a handler reading live debuggee state observes a coherent (mid-instruction-free) snapshot: - handled=false -> standard "not implemented" error - handled=true, err!= -> error response carrying err - handled=true, err== -> success response with body as the JSON body Generic + protocol-neutral: hosts namespace their own commands. nessy uses this to expose NES PPU / OAM / mapper / APU debug state to the chippy TUI debugger panels (nessy#28) without forking the protocol. Closes #416
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What
Add
AttachConfig.CustomRequestHandler— an opt-in extension point letting a hosting process serve its own DAP request commands over the same connection.Why
dap.Server.dispatchis a closed switch; unknown commands return "not implemented" with no host override. nessy needs to expose NES-specific debug state (PPU nametables/CHR/palette, OAM, mapper + APU registers, per-dot events) to the chippy TUI debugger panels (nessy#28) without forking the protocol.How
AttachConfig.CustomRequestHandler func(command string, args json.RawMessage) (body any, handled bool, err error), copied throughAttachExisting.defaultcase under the CPU lock → coherent state reads.handled=falsedefers to the standard "not implemented" error;handled=true,err!=nil→ error response;handled=true,err==nil→ success response withbody.Tests
TestCustomRequestHandler(success+body, asserts the lock is held during the handler, handled-with-error, handled=false → not-implemented) andTestCustomRequestHandler_NilDefersToNotImplemented. Full./dap/suite + vet + golangci-lint green.Closes #416