pipeline.Context.Path includes the query string under ext_proc and ext_authz, but not under the proxy listeners

[JoshSag]

Summary

pipeline.Context.Path holds a different value for the same request depending on the
listener:

listener (mode)	Path from	query string?	decoded?
forward / reverse proxy (proxy-sidecar)	r.URL.Path	no	yes
ext_proc (envoy-sidecar), 4 sites	raw :path pseudo-header	yes	no
ext_authz (waypoint)	AttributeContext.HttpRequest.path (documented as the full request target)	yes	no

GET /api/x?secret=1 gives plugins Path == "/api/x" under proxy-sidecar but
"/api/x?secret=1" under envoy-sidecar/waypoint. There is no Query field on
pipeline.Context, so any plugin behavior keyed on Path silently differs by
deployment mode.

Impact

Consumers diverging per mode today:

• context-guru: exact/suffix path gates miss /v1/messages?beta=true under
  Envoy modes only;
• opa: policies matching input.path == "/api/x" pass under proxy-sidecar,
  fail under envoy-sidecar/waypoint;
• ibac: the judge prompt interpolates pctx.Path, so under Envoy modes the
  judge LLM sees query parameters — potentially secrets carried in URLs.

Why it survived this long

Plugins kept absorbing it locally instead: bypass.Matcher strips the query since
birth (b7f79e49, as bypass-evasion canonicalization — accidentally shielding JWT
validation, the highest-traffic consumer), inference-parser hit it and fixed it
locally on 2026-08-26 (e957afd4 — its comment states the root cause verbatim:
"The listeners disagree on what Path holds"), and tool-prune hit it again on
2026-09-02 (ae3f0a35). Two independent plugin-level fixes for the same root cause
within one week says it's structural: Path should be fixed at the listeners, once.

Expected behavior

pctx.Path means the same thing in every listener mode: the URL path only, exactly
as the proxies produce it (query dropped, percent-decoded). Plugins that need the
query string should get an explicit channel (e.g. a future Query field) rather
than parsing Path.

Assisted-By: Claude (Anthropic AI) noreply@anthropic.com