[OmarAlJarrah]

Summary

Declared pagination and event-stream APIs state facts the IR had no field for, so every emitter would hard-code or guess them.

• Pagination inputs in the body, a page count and a stop rule (ir: pagination can't address a request-body input, a page count, or a stop condition #665).
  • ParamPath becomes InputPath, whose Param is optional: nil roots the path in the request body, where a search endpoint takes its cursor or page size. Parameter identity was already a ParamID (ir: parameters are bound by name, so same-named parameters in different locations are ambiguous #596).
  • Pagination gains TotalPages, counting pages where TotalCount counts items. It also gains Stop, the conditions that end iteration, a closed empty | no_next | short | total, any one ending the loop. An empty Stop states no rule, and the plan guesses none.
  • pass.Validate holds a path naming a parameter to the operation's own, as it held ParamPath. irverify reports a path naming nothing (ir/input-path-empty) and an undeclared stop (ir/unknown-page-stop).
  • The plan's PagePlan carries the input path and the stop rules.
• A stream's terminator (ir: an event stream's terminator value has no home #666). StreamDetail.Terminator holds the frame data that ends a stream verbatim, a sentinel that is no element, as an SSE data: [DONE] is. It sits beside Variant.Event.Terminal, which marks an event that is a variant. The stream plan compares each frame's data with it, and a frame matching it ends the stream undecoded.
• A stream sent only when asked (ir: a response that streams only when a request field asks for it has no home #667). StreamDetail.Condition holds the request input and the value asking for the stream, as a body's stream: true does. The operation otherwise returns its non-streaming contents. The issue's second option was weighed and declined: lowering the operation to two operations sharing one route mints an operation no position names, and a selector type the document never wrote. The stream plan offers the pair as two methods of one operation, each setting the input itself.

docs/ir/interaction-patterns.md states each rule, and docs/compilers/planned-lowerings.md notes that TypeSpec's body-level pagination decorators fill the body form.

No compiler fills these yet. The OpenAPI compiler reads no pagination or stream extension, which a promotion would do. On the golden spec (spec @319dc756), one operation offers JSON beside an event stream, none selects the stream with a body flag, no stream ends on [DONE], and two operations carry a pagination extension. That is the measurement behind #665's P2 and the others' P3.

Closes #665
Closes #666
Closes #667

Breaking

IRVersion moves to 0.33.0, after #1366's 0.32.0. A consumer pinned to the generation before this one refuses a document that sets any of these, and finds a body input's param absent where it required one. In Go, ParamPath is now InputPath, and its Param is a *ParamID.

Stack

Base: #1366, on #1361 and the rest of the IR stack. Merge in order.

Test plan

• go test on ir/..., pass/..., compilers/openapi/e2e, internal/... and cmd/.... The shape pin and the census were regenerated.
• New tests:
  • irverify.TestVerify_AnInputPathNamesARequestValue: a parameter, a body member, and neither, as a cursor and as a stream's condition.
  • irverify.TestVerify_APaginationStopIsOneIRDeclares.
  • StreamCondition.Value joins the value-carrier cases, so the payload rules reach it.
  • PageStop is classified among the IR's named string types.
• Push checklist: subject within 72 characters with the number, no artifact hits, skills_lint clean.
• CI.