Absolute-form requests on a reverse-proxy-only gateway listener reach the unauthenticated control route unjudged

[philcunliffe]

Deferred from the triage of PR #1271 (head ab56f4e83ea7481e59067f5bb728b4c8d59e8c92), review round 2 residual finding 3. Severity: low.

Where

hypaware-core/plugins-workspace/ai-gateway/src/proxy.js:411 (barrier, scoped by !absoluteFormShape) versus :432 (control gate, scoped by !absoluteForm).

Observed behavior

On a listener with no forward-proxy door (the default, proxy_mode off) absoluteForm is false while absoluteFormShape is true for a request line carrying an absolute URL. So POST http://attacker.example/_hypaware/ignore/session HTTP/1.1 with Host: attacker.example skips the Host judgment (shape-exempt at :411) and still reaches the unauthenticated control handler (door-scoped at :432 lets it through). The PR's test a reverse-proxy-only listener still path-routes absolute-form under a foreign Host covers only /v1/messages, never the control path.

Why deferral is safe

No capability changes: a browser cannot put an absolute URL on a request line, so the DNS-rebinding vector #1238 closed stays closed, and a local process able to send absolute-form can already reach the same route origin-form under Host: 127.0.0.1. What this exposes is a pre-existing tension between LLP 0247 #the-control-surface-never-answers-absolute-form (categorical) and #only-forward-proxy-listeners-serve-it (a pure reverse-proxy listener "behaves exactly as it always has"), which predates PR #1271. Aligning them changes what a default listener answers, a design change on an Accepted LLP, out of scope for #1238.

Acceptance condition

A new LLP (extending or superseding the relevant sections of 0247) decides whether a pure reverse-proxy listener answers absolute-form on the control path, and the code and a control-path absolute-form test match the decision: either the request is refused ahead of the control handler, or the exemption is recorded as intended with a test pinning the current behavior.

[philcunliffe]

Stuck: escalated to a design request, waiting on the decision

What neutral was doing. A fix attempt was admitted and stopped: this issue's
acceptance opens with "A new LLP (extending or superseding the relevant sections
of 0247) decides whether", so it is a design change, not a bug fix.

What was done. Request LLP 0382, "a doorless listener answers
absolute-form on the control path", proposed in #1374.

The premise was verified against the code at origin/master before writing
anything, and it holds exactly: proxy.js:373 sets
absoluteFormShape = !proxyMode && /^https?:\/\//i.test(requestUrl), :375
narrows it to absoluteForm = absoluteFormShape && forwardProxyDoor, :411
scopes the Host barrier by !absoluteFormShape so it is skipped, and :431
scopes the control gate by !absoluteForm so the request passes to
onControlRequest.

The contradiction in LLP 0247 is genuine, not merely apparent, which was tested
rather than assumed: #the-control-surface-never-answers-absolute-form is
categorical in both its heading and its rationale with no self-scoping, while
#only-forward-proxy-listeners-serve-it promises a doorless listener path-routes
the shape as before, and path routing answers /_hypaware/ locally because LLP
0066 #control-path puts the control check ahead of upstream matching. Both
cannot hold for this request.

Something the issue did not record. proxy.js:431 carries
@ref LLP 0247#the-control-surface-never-answers-absolute-form [implements]
while implementing the narrower door-scoped rule, so the annotation points at the
section it contradicts. It was left in place rather than silently repointed:
which way it should point is precisely the decision being requested.

Candidate resolutions, none chosen by the request:

1. The categorical rule governs, and absolute-form never reaches the control
   handler on any listener. Variant 1a falls through to path routing, where a
   catch-all upstream would receive it; variant 1b refuses ahead of the handler.
   Both change what a default listener answers, forking LLP 0233
   #proxy-mode-is-explicit.
2. The listener-scope rule governs: the exemption is recorded as intended and
   pinned with the control-path absolute-form test that PR Fix #1238: The ai-gateway proxy is a third loopback listener serving the control route and catch-all routing with no Host check #1271 never added.
   The cost is in the record, since "never" becomes "never where the door
   exists", the rationale is re-derived, and the @ref above is repointed.

Why this issue cannot proceed. No code change can be made without choosing,
and choosing is the decision #1374 exists to request. Marked stuck so the
reconciler stops re-admitting it and re-deriving the same escalation each tick.

How to unstick. Decide in #1374, or reply here; neutral monitors this thread
and will re-engage with your guidance on its next tick. This issue stays open
until the chosen resolution ships with its test.

Incidental, noticed while reading: LLP 0247's header still says Status: Draft
though it shipped in PR #797 and is @ref-implemented. Flipping it is a
permitted mechanical edit if someone wants the record accurate.