title: Model switch with tool continuity

scenario:
  id: model-switch-tool-continuity
  surface: models
  coverage:
    primary:
      - models.switching
    secondary:
      - runtime.tool-continuity
  objective: Verify switching models preserves session context and tool use instead of dropping into plain-text only behavior.
  successCriteria:
    - Alternate model is actually requested.
    - A tool call still happens after the model switch.
    - Final answer acknowledges the handoff and reread QA mission.
  docsRefs:
    - docs/help/testing.md
    - docs/concepts/model-failover.md
  codeRefs:
    - extensions/qa-lab/src/suite.ts
    - extensions/qa-lab/src/mock-openai-server.ts
  execution:
    kind: flow
    summary: Verify switching models preserves session context and tool use instead of dropping into plain-text only behavior.
    config:
      initialPrompt: "Read repo/qa/scenarios/index.yaml and summarize the QA scenario pack mission in one clause before any model switch."
      followupPrompt: "The harness has already requested the alternate model for this turn. Do not call session_status or change models yourself. Tool continuity check: use the read tool to reread repo/qa/scenarios/index.yaml, then mention the model handoff and QA mission in one short sentence."
      promptSnippet: "Tool continuity check"

flow:
  steps:
    - name: keeps using tools after switching models
      actions:
        - call: waitForGatewayHealthy
          args:
            - ref: env
            - 60000
        - call: reset
        - call: runAgentPrompt
          args:
            - ref: env
            - sessionKey: agent:qa:model-switch-tools
              message:
                expr: config.initialPrompt
              timeoutMs:
                expr: liveTurnTimeoutMs(env, 30000)
        - set: alternate
          value:
            expr: splitModelRef(env.alternateModel)
        - set: beforeSwitchCursor
          value:
            expr: state.getSnapshot().messages.length
        - call: runAgentPrompt
          args:
            - ref: env
            - sessionKey: agent:qa:model-switch-tools
              message:
                expr: config.followupPrompt
              provider:
                expr: alternate?.provider
              model:
                expr: alternate?.model
              timeoutMs:
                expr: resolveQaLiveTurnTimeoutMs(env, 30000, env.alternateModel)
        - call: waitForCondition
          saveAs: outbound
          args:
            - lambda:
                expr: "state.getSnapshot().messages.slice(beforeSwitchCursor).filter((candidate) => candidate.direction === 'outbound' && candidate.conversation.id === 'qa-operator' && hasModelSwitchContinuitySignal(candidate.text)).at(-1)"
            - expr: resolveQaLiveTurnTimeoutMs(env, 20000, env.alternateModel)
        - assert:
            expr: hasModelSwitchContinuitySignal(outbound.text)
            message:
              expr: "`switch reply missed kickoff continuity: ${outbound.text}`"
        - if:
            expr: "Boolean(env.mock)"
            then:
              - set: switchDebugRequests
                value:
                  expr: "await fetchJson(`${env.mock.baseUrl}/debug/requests`)"
              - set: switchRequest
                value:
                  expr: "switchDebugRequests.find((request) => String(request.allInputText ?? '').includes(config.promptSnippet))"
              - assert:
                  expr: "switchRequest?.plannedToolName === 'read'"
                  message:
                    expr: "`expected read after switch, got ${String(switchRequest?.plannedToolName ?? '')}`"
              - assert:
                  expr: "String(switchRequest?.model ?? '') === String(alternate?.model ?? '')"
                  message:
                    expr: "`expected alternate model, got ${String(switchRequest?.model ?? '')}`"
      detailsExpr: outbound.text