Trace terminal recovery and isolate neighbor resolver latency

docs/telemetry-recipes.md

@@ -103,6 +103,23 @@ sum by (job, instance) (increase(wakey_terminal_backpressure_total[15m]))
 This counts encounters, not their duration and not dropped chunks. A burst of
 image output can raise it while output still arrives intact through backpressure.
 
+Average duration of completed backpressure episodes, in seconds:
+
+```promql
+sum by (job, instance, outcome) (
+  rate(wakey_operation_duration_seconds_sum{operation="terminal_backpressure_wait"}[5m])
+)
+/
+sum by (job, instance, outcome) (
+  rate(wakey_operation_duration_seconds_count{operation="terminal_backpressure_wait"}[5m])
+)
+```
+
+An episode starts when the output channel is full and ends when the pending
+backlog drains or the relay disconnects. It is not per-frame network latency;
+unfinished episodes do not appear until they end. Keep the outcome grouping so
+disconnected episodes are not confused with successfully drained ones.
+
 ## Snapshots
 
 Device entries in successfully sent snapshots over the last hour:

docs/telemetry.md

@@ -100,6 +100,12 @@ existing debug events too; inspect them before enabling it broadly.
   with backoff and CC disconnect duration. Sending credentials is not an auth ACK;
   CC's authentication event is the authoritative result. DNS diagnostics are a
   separate lookup, not a measurement of the resolver inside WebSocket connect.
+- Terminal recovery uses `terminal_snapshot_generate` (encoded byte count),
+  transport-attachment spans, and `terminal_snapshot_request`. These measure
+  local work, not browser restoration or end-to-end image replay. Resume operation
+  success means credentials were queued for the worker. `terminal_backpressure_wait`
+  operation durations cover one full-queue backlog episode until it drains (`ok`)
+  or disconnects (`disconnected`); cancellation can retain the default `error` outcome.
 
 Instrument operation boundaries rather than individual rows or terminal chunks.
 Use `skip_all`, explicitly allow count fields, and instrument async futures rather