Add node override support for non-transport I/O node mocking

[briansrls]

Summary

This PR introduces node overrides to the execution framework, enabling flow tests to mock non-transport I/O nodes (like CLI tool operations) that aren't intercepted by the existing transport executor interception mechanism. It also adds flow verification tests that execute the full DAG in DryRun mode with mocked responses and verify terminal node outputs.

Key Changes

• Node Override Mechanism (core/exec/src/intercept.rs):

  • Added node_overrides: HashMap<String, HashMap<String, Value>> to BoundaryMocks
  • Implemented set_node_override() and get_node_override() methods to manage per-node output overrides
  • Node overrides force-mock any node regardless of port types, complementing transport executor interception

• Execution Logic (core/exec/src/execute.rs):

  • Modified execute_flat() to check for node overrides before transport executor interception
  • Node overrides take precedence and bypass normal execution for specified nodes
  • Supports both DryRun and Simulate execution modes

• MockSpec Extensions (core/test/src/mock_spec.rs):

  • Added TransportMock struct for transport executor node responses
  • Added ExpectedOutput struct for flow test assertions
  • Added NodeOverride struct for non-transport I/O node mocking
  • Extended MockSpec with transport_mocks, expected_outputs, and node_overrides fields
  • Implemented to_boundary_mocks() to convert MockSpec into executable BoundaryMocks
  • Added has_flow_test_data() helper to detect flow test scenarios

• Test Generation (core/testgen/src/codegen.rs):

  • Added flow_tests configuration flag to TestConfig
  • Implemented generate_flow_tests() to create flow verification tests
  • Flow tests build the DAG, inject mocked responses via DryRun, and verify terminal outputs

• Generated Tests (bootstrap, CI, makegen):

  • Replaced chain validation tests with flow verification tests
  • Added transport mocks for intercepted executor nodes (shell, file operations)
  • Added node overrides for non-transport nodes (e.g., clippy_lint CLI tool)
  • Added expected output assertions for terminal nodes
  • Updated test configuration to enable flow tests and disable chain tests

Implementation Details

• Execution Order: Node overrides are checked first in execute_flat(), before transport executor interception. This allows tests to completely replace node behavior when needed.
• MockSpec Conversion: The to_boundary_mocks() method maps both transport mocks (port-level) and node overrides (full-node) into a single BoundaryMocks instance for execution.
• Flow Test Pattern: Tests follow a consistent pattern: build DAG → convert MockSpec to BoundaryMocks → execute in DryRun mode → assert terminal outputs match expectations.
• Backward Compatibility: Existing boundary mock and resource simulation functionality remains unchanged; node overrides are purely additive.

https://claude.ai/code/session_016u4exV48KcTPNZuiN71gdX

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Skip tool acquisition when node override is used

Because node overrides are only checked inside this block, DryRun/Simulate still run acquire_node_tools earlier in execute_flat for any requires_tools node (e.g., clippy_lint). That means a flow test with a node override will still perform real tool checks/installs before the override takes effect, which can fail in CI or mutate the environment despite the mock. Consider bypassing tool acquisition when a node override is present (or moving the override check before tool acquisition in DryRun/Simulate) so mocked non-transport nodes truly avoid I/O.

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