Triage & merge plan: @ferponse ADK-middleware / transport contributions

[contextablemark]

Thank you @ferponse for the submissions and I apologize for the delay in responding, though
even this response is more of a placeholder as your requests can't be considered in bulk and, with
most of them being features rather than fixes, some require more consideration than others.

Why this is one issue

@ferponse opened 8 PRs + 5 protocol-design issues (Jul 1–2), all opt-in / default-off,
and pinged me on each. The PRs are individually reasonable, but nearly all of them append a
flag to the same three files — so they conflict with each other and, if eventually accepted,
have to be merged in sequence, re-running the middleware suite between each. This issue is
the single home for hat sequence; the far-reaching protocol-direction questions live in a separate
Proposal discussion (linked at the bottom).

File hotspots (why serial)

File	Region	PRs that collide
event_translator.py	import block + top of translate()	#2104, #2073, #2076, #2099
adk_agent.py	__init__ / from_app signature	#2108, #2102, #2099, #2076
endpoint.py	capabilities_endpoint transport dict	#2097, #2085 (+ #2108 feeds it)
run flow	RUN_FINISHED / completion	#2102, #2076, #2085

Merge order

Rebasing later PRs onto the earlier merges is on the contributor.

⛔ Precursor — land first, standalone

• chore · Bump ag-ui-protocol minimum pin → >=0.1.18 (ideally 0.1.19) in
  integrations/adk-middleware/python/pyproject.toml. Unblocks feat(ag-ui-adk): surface HITL pauses as AG-UI interrupts on RUN_FINISHED.outcome #2102's imports of
  Interrupt / RunFinishedInterruptOutcome and de-risks all interrupt-related work.

Phase 1 — event_translator.py chain (cleanest)

• feature · feat(ag-ui-adk): emit ACTIVITY_SNAPSHOT/DELTA from ADK custom_metadata markers #2104 — ACTIVITY_SNAPSHOT/DELTA from custom_metadata markers · closes feat(ag-ui-adk): emit ACTIVITY_SNAPSHOT/DELTA from ADK custom_metadata markers #2103
  → merge first. Ask: add a malformed-delta test + assert activity-precedes-text ordering.
• fix · fix(adk-middleware): emit REASONING_ENCRYPTED_VALUE for function_call thought signatures #2073 — REASONING_ENCRYPTED_VALUE for thought signatures · closes [adk-middleware] REASONING_ENCRYPTED_VALUE never emitted: thought signatures are on function_call parts, not thought parts #2072
  → Ask: add self._emitted_signature_tool_call_ids.clear() to reset() (unbounded growth
  across sequential runs). Optionally handle streaming-fc-args id remap.
• feature · feat(adk): opt-in STEP_STARTED/STEP_FINISHED for workflows (Sequential/Parallel/Loop + sub-agents) — non-breaking, ADK 1.x & 2.x #2076 — opt-in STEP_STARTED/FINISHED for workflows · closes Feature Request: ADK middleware - no STEP_STARTED/STEP_FINISHED for workflow / multi-agent runs #2075
  → Ask: also call finalize_step_events() on the except / RUN_ERROR path so an exception
  can't leave steps open.
• feature · feat(ag-ui-adk): opt-in RAW passthrough of the untranslated ADK event #2099 — RAW passthrough of untranslated ADK events · closes feat(ag-ui-adk): opt-in RAW passthrough of the untranslated ADK event #2098
  → Ask: LRO/HITL events bypass translate() and get no RAW event — close the gap or document
  it. Needs my scope sign-off (author explicitly requested it).

Phase 2 — adk_agent.py config

• feature · feat(ag-ui-adk): auto-discover AgentCapabilities from the wrapped ADK agent (opt-in) #2108 — auto-discover AgentCapabilities · closes Auto-discover AgentCapabilities from the wrapped ADK agent (opt-in) #2107
  → Ask: flag-off is not "100% unchanged" — capabilities={} now returns None; make it an
  explicit is not None check + a test. Fix the description: the factory is from_app(),
  not the nonexistent create().
• feature · feat(ag-ui-adk): surface HITL pauses as AG-UI interrupts on RUN_FINISHED.outcome #2102 — HITL pauses → interrupts on RUN_FINISHED.outcome · closes feat(ag-ui-adk): surface HITL pauses as AG-UI interrupts on RUN_FINISHED.outcome #2101
  → Blocked on the precursor pin bump. Ask: add an end-to-end test that drives a real HITL
  pause through the consumer loop; reuse the authoritative HITL marker set instead of treating
  every unresolved TOOL_CALL_END as an interrupt.

Phase 3 — endpoint.py transports (reconcile against #2108's capabilities path)

• feature · feat(transport): implement httpBinary (protobuf-over-HTTP) on the Python side (ag_ui encoder + ag-ui-adk) #2097 — httpBinary (protobuf-over-HTTP) on the Python side · closes feat(transport): implement httpBinary (protobuf-over-HTTP) on the Python side (ag_ui encoder + ag-ui-adk) #2094
  → Ask: don't advertise httpBinary unless the protobuf extra is importable (else clients
  negotiate a transport that fails with an empty stream); surface an error frame on binary
  encode failure; drop the dead capabilities guard.
• feature · feat(transport): WebSocket transport for ag-ui-adk and @ag-ui/client #2085 — WebSocket transport · closes feat(transport): WebSocket support for ag-ui-adk and @ag-ui/client #2084 · request changes, land last
  → Must: fix the 3 broken test_capabilities.py tests; make transport advertisement additive
  (no force-override / in-place mutation / dead branch); add real /ws + WebSocketAgent
  tests; and either implement or delete the single-socket HITL claim. Pending transport-roadmap
  decision (see discussion).

Protocol-direction questions (handled separately)

The 5 design issues — #2154, #2146, #2106, #2105, #2091 — touch the core protocol surface and
are being decided together, not piecemeal:

➡️ Proposals discussion #2161