fed-sx-m1: Step 8d-dispatch-get — format-aware actor/artifact/projection/list responses + dispatch/3 refactor + 17 tests

plans/fed-sx-milestone-1.md

@@ -521,7 +521,7 @@ publish(ActorId, ActivityRequest) ->
 - [x] **8d-dispatch-cap** — `capabilities_body_for/1` returns distinct stubs per format (json `{...}`, sx `(...)`, cbor `A1 64 caps 69 fed-sx-m1`); activity_json shares the json body. Route intercepts GET capabilities to thread the Accept format through `accept_format_from/1`. `next/tests/http_capabilities_format.sh` (13 cases).
 - [x] **8d-content-type** — `content_type_for/1` maps format atoms to MIME-type binaries (text/plain, application/json, application/activity+json, application/sx, application/cbor). `ok_response/2(Body, Format)` builds a 200 response with the right Content-Type header. `next/tests/http_content_type.sh` (13 cases).
 - [x] **8d-dispatch-post** — POST `/activity` now threads the Accept format through both kernel-present (`cid_response_for/2` → `{"cid":"<cid>"}` for json / `(cid "<cid>")` for sx / raw bytes for cbor) and kernel-absent (`post_activity_response_for/1` → `{"status":"stub"}` / `(status "stub")` / etc.) paths. `next/tests/http_post_format.sh` (13 cases) covers shape + Content-Type for both stub and publish paths.
-- [ ] **8d-dispatch-get** — Same treatment for `actor_doc_response`, `artifact_response`, `projection_response` on the GET paths.
+- [x] **8d-dispatch-get** — `actor_doc_response_for/2`, `artifact_response_for/2`, `projection_response_for/2`, `projections_list_response_for/1`. `dispatch` refactored to `/3` to thread Format; route extracts Format once and passes it down. `next/tests/http_get_format.sh` (17 cases) covers per-format bodies + Content-Type + end-to-end GETs with Accept headers.
 
 **Deliverables:**
 
@@ -1000,6 +1000,7 @@ A few things still under-specified; resolve as work begins.
 Newest first. One line per sub-deliverable commit. Erlang conformance gate
 (`bash lib/erlang/conformance.sh`) must remain 729/729 on every entry.
 
+- **2026-05-28** — Step 8d-dispatch-get: format-aware versions of every GET response builder. `actor_doc_response_for/2`, `artifact_response_for/2`, `projection_response_for/2`, `projections_list_response_for/1`. Each produces `{"key":"value"}` (json/activity_json), `(key "value")` (sx), raw payload bytes (cbor stub), or the existing text form. `dispatch` refactored to `/3` with a backward-compat `dispatch/2` wrapper. Route extracts Format via `accept_format_from/1` once at the top and threads it through dispatch. End-to-end GETs with `Accept: application/json` / `application/sx` verified for all three dynamic-prefix routes + the projections-list bare-path route. Step 8d effectively complete — format dispatch + Content-Type live on every non-static response. `next/tests/http_get_format.sh` 17/17. Erlang conformance 729/729.
 - **2026-05-28** — Step 8d-dispatch-post: `handle_post_activity` extracts the Accept format via `accept_format_from/1` and threads it into `publish_if_kernel/2`. Both success paths emit format-specific bodies: `cid_response_for/2` produces `{"cid":"<cid>"}\n` (json/activity_json), `(cid "<cid>")\n` (sx), raw CID bytes (cbor), or the existing text form; `post_activity_response_for/1` mirrors for the kernel-absent stub. Each response carries the matching Content-Type. End-to-end POSTs with `Accept: application/json` / `application/sx` verified through the full HTTP→nx_kernel→publish→cid_response_for chain. `next/tests/http_post_format.sh` 13/13. Erlang conformance 729/729.
 - **2026-05-28** — Step 8d-content-type: `content_type_for/1` maps format atoms to MIME-type binaries — text/plain (10b), application/json (16b), application/activity+json (25b), application/sx (14b), application/cbor (16b); unknown formats fall through to text/plain. `ok_response/2(Body, Format)` constructs a 200 response with `{headers, [{<<"content-type">>, MIME}]}`. Lowercase header key matches how the BIF wrapper normalises request headers. `ok_response/1` still produces the empty-headers shape — backward compat preserved. `next/tests/http_content_type.sh` 13/13. Erlang conformance 729/729.
 - **2026-05-28** — Step 8d-dispatch-cap: `capabilities_body_for/1` returns distinct byte sequences per format — text reuses the existing `capabilities_body/0`; json/activity_json share `{"caps":"fed-sx-m1"}`; sx returns `(caps "fed-sx-m1")`; cbor returns a minimal `A1 64 caps 69 fed-sx-m1` map. Route now intercepts GET `/.well-known/sx-capabilities` to pull the Accept format via `accept_format_from/1` and dispatch through `capabilities_body_for`. Unknown formats fall back to text. POST capabilities still 404 (only GET handled). `next/tests/http_capabilities_format.sh` 13/13 verifies all formats + the intercept + no-Accept default. Content-Type headers not yet set (8d-dispatch-rest covers headers + applying the same shape to actor/artifact/projection/cid responses). Erlang conformance 729/729.