[1/N] [List API] docs(list): define request context read model

[albertywu]

Summary

Updates List API RFC with:

• Proto contract
• RequestContext, an immutable data store that captures request context like queue & changeIDs. Data here is projected onto RequestSummary at write time.
• Changed List time-window semantics from lifecycle overlap to requests admitted during [start_time_ms, end_time_ms). Doing lifecycle-overlap queries as previously specified requires a lot of additional complexity to make performant, so is deferred.

Stack

1. @ [1/N] [List API] docs(list): define request context read model #310
2. [2/N] [List API] feat(context): add immutable request admission store #302
3. [3/N] [List API] feat(summary): project request logs from admission context #303
4. [4/N] [List API] feat(gateway): expose List API from request summaries #304
5. [5/N] [List API] test(e2e): cover gateway List API #305
6. [6/N] [List API] docs(service): document gateway List API read model #306

[Copilot]

Pull request overview

This PR updates the SubmitQueue Gateway List API RFC to more explicitly define the gateway-owned read model, including an immutable request-admission context record that can be joined with append-only request-log events to project a queryable request-summary table for the List RPC.

Changes:

• Expands the RFC’s proposed wire contract (proto sketch) for List, including request/response messages and sorting options.
• Introduces and motivates an immutable RequestContext admission record as the source of truth for queue + change URIs + admission time.
• Refines the read-model projection/pagination/indexing discussion (idempotent projection, lifecycle-overlap semantics, keyset pagination).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

doc/rfc/submitqueue/list-api.md:254

• The RFC ends with a ## Why Not Return Timelines header but no content. This reads like an incomplete section and can confuse readers; either remove the header or add the intended rationale text.

## Why Not Return Timelines

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

doc/rfc/submitqueue/list-api.md:256

• The RFC ends with a "## Why Not Return Timelines" heading but no body text, which leaves the rationale incomplete and reads like an accidental truncation.

## Why Not Return Timelines