fix(flows): stop condition nodes starving downstream =item + dry-run routing-divergence warning (B15)

[graycyrus]

Fixes B15 — a downstream node was silently starved after a condition, so an agent's input_context:"=item" resolved null → it hallucinated generic content ("@JDoe", not the real data). Proven on the "funny reminders" flow: every run generated a fake reminder. Two coupled tinyflows engine bugs + a dry-run blind spot.

Root cause (elegant — two bugs compound)

• A1 (engine): a condition with only a true edge was lowered as an unconditional edge → the successor always ran, but collect_input port-matched true vs the emitted false and dropped the items → the successor ran with empty input. (Every existing condition test wires both edges, so this single-edge path was never covered.)
• A2 (condition node): field was read as a literal key, so field:"=item.assignee" did get("=item.assignee") → always None → always false. Combined with A1 → always-false + always-runs-empty → =item null.

Fixes

• tinyflows (via #5, pin bumped to 56d81df): a single non-main edge is now a conditional edge with an END fallback → a true-only condition acts as a filter (items flow on true, run ends on false); the condition node now resolves =-expressions in field.
• openhuman dry-run: DryRunWorkflowTool now emits a routing-divergence warning when an agent/tool_call node never executed because a condition routed the mock data away — the exact class the dry-run missed (mock item shape ≠ real). Pure warning, doesn't flip ok.

Verification

tinyflows 304 lib + 12 doctests + --all-features e2e pass · openhuman cargo check clean · flows:: 392 pass (+ dry_run_warns_on_unexercised_agent_after_condition).

Summary by CodeRabbit

• Bug Fixes

  • Dry-run checks now surface warnings when a workflow’s expected path does not match the path actually taken during validation.
  • Failure messages now include these routing warnings, making skipped steps easier to spot.

• Tests

  • Added coverage for workflows where a branch is not exercised during dry-run validation and where it is exercised as expected.

• Chores

  • Updated an internal dependency snapshot.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

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Run ID: ffcfeb90-1756-4f81-b6f8-7cff59d9286c

📥 Commits

Reviewing files that changed from the base of the PR and between 0788443 and fb47a46.

📒 Files selected for processing (3)

• src/openhuman/flows/builder_tools.rs
• src/openhuman/flows/builder_tools_tests.rs
• vendor/tinyflows

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📝 Walkthrough

Walkthrough

DryRunWorkflowTool now detects "routing-divergence" cases where agent/tool_call nodes never execute because an upstream condition node takes a different branch under mock trigger input. A new find_upstream_condition helper attributes each unexecuted node to its nearest upstream condition, and results (both ok:true and ok:false) include a routing_divergence_warnings field with explanatory messages. Logging and tests were updated accordingly. The vendor/tinyflows submodule pointer was bumped.

Changes

Routing-Divergence Warning Feature

Layer / File(s)	Summary
Routing-divergence detection logic src/openhuman/flows/builder_tools.rs	Documents and implements detection of unexecuted agent/tool_call nodes via a new find_upstream_condition helper that walks predecessor edges to attribute unexecuted nodes to the nearest upstream condition, and logs a routing_divergence_warning_count.
Result JSON and messaging updates src/openhuman/flows/builder_tools.rs	Adds routing_divergence_warnings to both ok: false and ok: true result JSON, extends the ok: false message and adds a note in the ok: true case explaining the warnings.
Tests for warning presence/absence src/openhuman/flows/builder_tools_tests.rs	Adds two tests: one asserting a routing-divergence warning appears when a condition skips a downstream agent, another asserting an empty warnings array when the condition branch executes all downstream nodes.
Submodule pointer bump vendor/tinyflows	Updates the tinyflows submodule to a new commit.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Possibly related PRs

• tinyhumansai/openhuman#4586: Both PRs modify dry_run_workflow in builder_tools.rs and extend builder_tools_tests.rs with additional dry-run diagnostic assertions.
• tinyhumansai/openhuman#4590: Both PRs extend dry_run_workflow diagnostics for agent-related execution issues in the same file.

Suggested labels: rust-core, bug

Poem

A condition forked, an agent slept,
No warning raised, no watch was kept.
Now I hop the graph, node by node,
Tracing branches down each road.
🐇 "Divergence found!" I thump with cheer —
unexecuted paths, at last made clear.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title matches the main changes: fixing condition-node routing issues and adding dry-run routing-divergence warnings.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[chatgpt-codex-connector]

Preserve fan-in barriers for single conditional edges

When this bumps TinyFlows to 56d81df, its new single non-main edge lowering routes directly with add_conditional_edges before the existing fan-in check. In a graph where a true-only condition feeds a merge/fan-in that also has another independent predecessor, the merge can now be scheduled as soon as the condition branch fires instead of waiting for the other predecessor, so it observes partial input and produces an incomplete merge. The default-main path in the same TinyFlows change still applies incoming_counts/add_waiting_edge, so the new conditional path needs equivalent fan-in handling for the taken branch.

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