Desktop sessions can run against different saved providers at the same time, so the runtime selection must remain scoped to the session from WebSocket startup through the CLI request path. This adds parallel-session regression coverage, a browser-driven fake-provider E2E, and refreshes idle connected sessions after provider saves so stale provider edits are reapplied without disturbing active turns.
Constraint: Desktop provider credentials must stay session-scoped and must not leak across concurrent CLI child processes
Rejected: Rely on provider test connectivity alone | it does not exercise the desktop WebSocket, session runtime, or CLI request path
Confidence: high
Scope-risk: moderate
Directive: Do not change runtime selection persistence or provider env injection without rerunning the parallel provider browser E2E
Tested: cd desktop && bun run test src/stores/providerStore.test.ts src/stores/chatStore.test.ts
Tested: CLAUDE_CONFIG_DIR=/Users/nanmi/.claude bun test src/server/__tests__/conversations.test.ts --timeout 30000
Tested: desktop/scripts/e2e-parallel-providers-agent-browser.sh
Tested: bun run quality:smoke --provider-model custom:main:custom-main --provider-model minimax:main:minimax-main
Tested: cd desktop && bun run lint
Tested: git diff --check
Not-tested: bun run verify passes fully; coverage lane still fails on the existing agent-utils ratchet below baseline
