Plugin marketplace `marketplace.git` returns 404 on all git paths, though the plugin is registered and readable via the data API (eastus)

Start by reproducing the marketplace.git info/refs, HEAD, and plugin paths in East US with the documented token, comparing them with the /plugins data API response. Check both HTTP/2 and authenticated HTTP/1.1 behavior, including the git client path. Done means the generated marketplace repository is discoverable and cloneable over git's default HTTP/1.1, while the existing plugin remains readable.

Description

The plugin marketplace endpoint is enabled and a plugin is registered and fully readable through the data API, but the generated marketplace.git repository returns 404 on every git path — so git clone / /plugin marketplace add cannot discover any refs. The repo appears to never be generated/served, even though the plugin exists.

This looks like the same family as #79 (data-plane 404 on the MCP /v0.1/servers endpoint, fixed "to all regions" on 2026-06-25) — but on the plugin-marketplace surface, which is still 404ing in East US.

Environment

• API Center, region East US (<service>.data.eastus.azure-apicenter.ms)
• Plugin marketplace endpoint: enabled (Data API settings)
• Portal access method: Microsoft Entra ID
• Inventory: 1 MCP server + 6 skills + 1 plugin bundling all 7
• Token used for tests: aud=https://azure-apicenter.net, scp=Data.Read.All (obtained via the managed-portal sign-in)

Reproduction steps

1. Enable Plugin marketplace endpoint (Data API settings) with a registered plugin that bundles skills + an MCP server.
2. Acquire a valid azure-apicenter.net / Data.Read.All delegated token.
3. Confirm the plugin is readable via the data API (works — see below).
4. Request the marketplace git paths with the same token (over HTTP/2 — see HTTP note):

GET …/workspaces/default/plugins/marketplace.git/info/refs?service=git-upload-pack   -> 404
GET …/workspaces/default/plugins/marketplace.git/HEAD                                 -> 404
GET …/workspaces/default/plugins/marketplace.git/.claude-plugin/marketplace.json      -> 404
GET …/workspaces/default/plugins/marketplace.git                                       -> 400 "The gitPath field is required."
GET …/workspaces/default/plugins                                                       -> 200  (returns the plugin)

Expected behavior

git clone …/marketplace.git (and the info/refs discovery) returns the generated marketplace repo — marketplace/ with .claude-plugin/, .github/, and a folder per plugin — as documented in Enable Discovery of Plugins from API Center Plugin Marketplace.

Actual behavior

All git paths return 404 (application/problem+json), so git clone / /plugin marketplace add fails with "repository not found". The data API returns the plugin correctly, so the plugin is registered — the git repo is simply not generated/served.

Sample 404 body:

{"type":"https://tools.ietf.org/html/rfc9110#section-15.5.5","title":"Not Found","status":404,"traceId":"00-455a74e4…"}

The data API returns the plugin fine (proving registration is correct):

{"value":[{"name":"client-insights","version":"1.0.0","resources":[
  {"resourceId":"/workspaces/default/skills/<skill-1>","kind":"skill"},
  … 5 more skills …,
  {"resourceId":"/workspaces/default/apis/<mcp-server>","kind":"mcp"}]}]}

traceIds (East US)

00-455a74e436d1…
00-4ffc7ae760d1…
00-f7160ce7122c…
00-fd4e3ffe362280b2d0b325d8507dc4be-7a0b988ebfd5bdac-00

(Subscription/tenant available on request.)

What we already ruled out

• Not auth — 404 (not 401/403); the same token reads …/plugins with 200.
• Not config — endpoint enabled, plugin bundle complete (7 resources), visibility open, portal Entra access configured + published. Per the docs there is no separate publish/sync/RBAC/MCP-endpoint step.
• Not transient — reproduced repeatedly over ~1.5h with fresh tokens.
• Toggle off→save→on→save the marketplace endpoint: no effect (still 404).
• Persists after #79's fix landed.

Secondary issue — authenticated HTTP/1.1 requests return empty-body 500

Independently: authenticated requests over HTTP/1.1 (git's default, plus curl / PowerShell Invoke-WebRequest / python urllib) return an empty-body 500 (no x-ms-request-id) for all data-plane paths. The same token over HTTP/2 returns correct codes (200 for …/plugins, 404 for the marketplace). Unauthenticated HTTP/1.1 cleanly 401s — it's the presence of an Authorization header over HTTP/1.1 that 500s.

This will block git clone even once the 404 is fixed (git negotiates HTTP/1.1 by default), so it's worth addressing alongside. Workaround: git config http.version HTTP/2.