Case Study·production

Single-Session Multi-Channel Calling

How the hybrid telephony work moved channel selection out of session init — enum state, session-preserving driver swaps, and callMedium attribution across logs and analytics.

Date2026-04

Reading TimeN/A

Statusproduction

StackFlutter, Dart, State Machines+1

In-session driver swap

Mode switch

[High Confidence]

callMedium on activity and reports

Attribution

[High Confidence]

Companion write-up for Hybrid Telephony Workflows.

Challenge: session-level coupling

Channel used to be a flag baked into session creation:

flowchart TD
  LegacySession[Session Instantiation] -->|Hardcoded Channel Flag| BoundMode{Bound Channel Mode}
  BoundMode -->|Cellular| CellularSession[Cellular Session]
  BoundMode -->|Cloud| CloudSession[Cloud Session]
  CellularSession -->|Mode Switch| DestroySession[Forced Teardown and Re-Auth]
  CloudSession -->|Mode Switch| DestroySession

That caused forced re-auth, cache/sync loss risk on teardown, and reporting forks that disagreed on which medium a call used.

Solution: session-preserving orchestrator

Mode becomes runtime state on one session. Drivers swap; Hive, tokens, and sync queues stay.

sequenceDiagram
  participant User as Operator UI
  participant Orchestrator as Session Orchestrator
  participant Driver as Channel Driver
  participant Telemetry as Telemetry and Reporting

  User->>Orchestrator: Request channel action
  Orchestrator->>Orchestrator: Check session and permissions
  alt Cellular
    Orchestrator->>Driver: Cellular intent
  else Cloud
    Orchestrator->>Driver: Cloud virtual service
  end
  Driver->>Telemetry: Tag payload with callMedium
  Telemetry->>User: UI updates; session intact

Primitives

Enum model — SIM / Cloud / Hybrid
Driver orchestrator — re-inits transport without resetting the user session
CallMediumSelector — default or per-interaction override
callMedium attribution — events, activity logs, exports, dashboards

Outcomes (high confidence)

Operators change medium without logout
Reporting uses one attribution field instead of parallel mode branches
Admin permission/allocation changes no longer imply client re-login storms

See the project page for the shorter product-facing summary.