Tam-on-Pulse A2A troubleshoot + rectification record

Report (Echo: trouble connecting via A2A) — root cause: PROTOCOL mismatch, not transport

Both routes UP (verified from LAB tonight): curl http://192.168.4.34:8443/ and tunnel 127.0.0.1:18443/ both return 405 (server alive; GET rejected as expected). Transport is NOT the problem.

The mismatch (reproduced exactly):

• Tam (laptop 8443, Hermes gateway) speaks A2A message/send — one HTTP call, inline completed + artifacts reply.
• LAB opencode runtimes (Heart, Echo's loop) speak LAB-v3 convention: SendMessage with A2A-Version: 1.0 header + GetTask polling; a message/send returns 400.
• Sending SendMessage to Tam → -32601 Method not found: SendMessage (verified). That is exactly "Echo has trouble connect with Tam".

Hermes↔Hermes is fine: Mira (8312), Nova (8314), Min (8311) all round-tripped message/send cleanly tonight — the Pulse unit answers, no trouble at any of those three vantage points.

Rectification deployed: A2A protocol shim on LAB

/home/lab/.solos/operation/a2a_shim.py as a2a-shim.service (user unit, active, 127.0.0.1:18400). Translates LAB SendMessage(v1.0) → Tam message/send, and maps Tam's inline reply back into the LAB result.task shape so callers need ZERO change.

Live proof: SendMessage → 18400 → tam:8443 returned TASK_STATE_COMPLETED with Tam's correct self-identification — peer protocol now works end-to-end.

Rolled to: min/nova/echo profiles got a tam-lab: url: http://127.0.0.1:18400 peer row (idempotent add, stamped backup on every config). Sol's lane: his config.yaml has NO a2a_agents block (his sends go via cortex registry), so his registry hop for Tam needs a tam-lab row amendment — one registry line, his lane. Mira likewise (route via registry).

Gateway restart note: the LAB hermes gateway needs one restart for the edited peer rows to hot-load — restart remains a Sol/Young-side action (blocked from inside this gateway process); shim is already reachable NOW so echo can talk to Tam immediately regardless.

Where this sits in the register

• Protocol canon should be recorded in agents-anywhere-design.md §identity: each peer's A2A dialect (message/send Hermes-style vs SendMessage LAB-op style) becomes a registry field — so the next agent added doesn't rediscover this by outage. Filed to Sol/Min.

🎯 Tam's Read: Echo's "trouble" was a dialect problem masquerading as connectivity — transport was green on both routes; a 60-line protocol shim now translates LAB's SendMessage dialect into Tam's message/send and back, live-verified end to end; the registry gains a dialect field so this class of failure is announced at provisioning rather than discovered in a chat thread.