---
phase: 36-fan-out-pyo3-bridge
verified: 2026-03-29T12:00:00Z
status: passed
score: 9/9 must-haves verified
re_verification: false
---

# Phase 36: Fan-Out PyO3 Bridge Verification Report

**Phase Goal:** LiveBarEngine dispatches every completed bar to both ChannelSink (for Python) and ClickHouseWriterSink (for CH), with writer metrics and config flowing through the PyO3 bridge
**Verified:** 2026-03-29T12:00:00Z
**Status:** passed
**Re-verification:** No — initial verification

---

## Goal Achievement

### Observable Truths

| #   | Truth                                                                                             | Status   | Evidence                                                                                                                                                                                  |
| --- | ------------------------------------------------------------------------------------------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1   | Pre-write guards reject bars with timestamps outside [1e15, 2.5e15] microsecond range             | VERIFIED | `guards.rs` lines 39-56: MIN_US=1e15, MAX_US=2.5e15; 5 guard unit tests all pass                                                                                                          |
| 2   | Pre-write guards reject bars with negative volume                                                 | VERIFIED | `guards.rs` lines 58-68; test `test_guard_negative_volume_rejected` passes                                                                                                                |
| 3   | Fan-out dispatches completed bars to optional BarSink vector alongside ring buffer                | VERIFIED | `trade_dispatch.rs` lines 73-78 and 114-118: ring buffer push first, then `dispatch_to_sinks()`. Also in `puck.rs` lines 110-111 and 145-146, and `mod.rs` lines 615-638 (fill_from_rest) |
| 4   | ClickHouseWriterSink errors never block ring buffer bar delivery to Python                        | VERIFIED | `dispatch_to_sinks()` (guards.rs lines 81-113): errors logged but not propagated; ring buffer push always precedes sink call in all 3 emission paths                                      |
| 5   | Ouroboros mode hardcoded to "aion" in ClickHouseBarRow (already done in Phase 34)                 | VERIFIED | `row.rs` line 270: `ouroboros_mode: "aion".to_string()`; test `test_ouroboros_mode_is_aion` at line 458                                                                                   |
| 6   | ClickHouseWriterConfig reads OPENDEVIATIONBAR_CH_HOSTS from env (already done in Phase 34)        | VERIFIED | `mod.rs` lines 146-158: `std::env::var("OPENDEVIATIONBAR_CH_HOSTS")` conditional creation                                                                                                 |
| 7   | Python calling `stream_manager.get_metrics()` sees `ch_writer_*` keys updating in real time       | VERIFIED | `stream_manager.rs` lines 572-598: 6 `ch_writer_*` keys inserted from AtomicU64 loads; `stream_manager_bindings.rs` line 555 passes entire HashMap to PyDict                              |
| 8   | When clickhouse-sink feature is disabled, `get_metrics()` works unchanged (no `ch_writer_*` keys) | VERIFIED | All `ch_writer_*` insertion blocks gated with `#[cfg(feature = "clickhouse-sink")]`; clean build confirmed without feature                                                                |
| 9   | Root Cargo.toml streaming feature propagates clickhouse-sink to opendeviationbar-streaming        | VERIFIED | `Cargo.toml` line 190: `streaming = [..., "opendeviationbar-streaming/clickhouse-sink", ...]`                                                                                             |

**Score:** 9/9 truths verified

---

### Required Artifacts

| Artifact                                                              | Expected                                                     | Status   | Details                                                                                                       |
| --------------------------------------------------------------------- | ------------------------------------------------------------ | -------- | ------------------------------------------------------------------------------------------------------------- |
| `crates/opendeviationbar-streaming/src/clickhouse_writer/guards.rs`   | Pre-write guard validation functions                         | VERIFIED | 206 lines; exports `validate_bar_for_write` and `dispatch_to_sinks`; 6 unit tests                             |
| `crates/opendeviationbar-streaming/src/clickhouse_writer/mod.rs`      | `pub mod guards` present                                     | VERIFIED | Line 19: `pub mod guards;`                                                                                    |
| `crates/opendeviationbar-streaming/src/live_engine/trade_dispatch.rs` | Fan-out dispatch + `ExtraSinks` type alias                   | VERIFIED | Lines 17-20: `ExtraSinks` type alias; lines 73-78, 114-118: fan-out calls                                     |
| `crates/opendeviationbar-streaming/src/live_engine/mod.rs`            | LiveBarEngine with `extra_sinks` field + `ch_writer_metrics` | VERIFIED | Lines 96-99: both fields present; lines 144-158: conditional creation; line 964: `ch_writer_metrics()` method |
| `crates/opendeviationbar-streaming/src/live_engine/symbol_task.rs`    | `extra_sinks` parameter threaded through                     | VERIFIED | Line 46: parameter present; 7 call sites pass `&extra_sinks`                                                  |
| `crates/opendeviationbar-streaming/src/stream_manager.rs`             | `get_combined_metrics()` includes 6 `ch_writer_*` keys       | VERIFIED | Lines 573-598: all 6 keys present; 2 tests verify key presence/absence                                        |
| `Cargo.toml`                                                          | `streaming` feature includes `clickhouse-sink`               | VERIFIED | Line 190: confirmed present                                                                                   |

---

### Key Link Verification

| From                                       | To                                         | Via                                                       | Status   | Details                                                                                                            |
| ------------------------------------------ | ------------------------------------------ | --------------------------------------------------------- | -------- | ------------------------------------------------------------------------------------------------------------------ |
| `trade_dispatch.rs`                        | `guards.rs`                                | `dispatch_to_sinks()` called before sink dispatch         | VERIFIED | Lines 75-77 and 115-117: `dispatch_to_sinks()` called (which internally calls `validate_bar_for_write` then sinks) |
| `trade_dispatch.rs`                        | `BarSink::on_bar()`                        | Fan-out loop over `extra_sinks` via mutex                 | VERIFIED | `dispatch_to_sinks()` in guards.rs lines 88-111: iterates sinks and calls `sink.on_bar(bar)`                       |
| `LiveBarEngine::new()`                     | `ClickHouseWriterSink::new()`              | Conditional creation when clickhouse-sink feature enabled | VERIFIED | `mod.rs` lines 146-158: `ClickHouseWriterSink::new(ch_config)` called when env var set                             |
| `stream_manager.rs get_combined_metrics()` | `FlushThreadMetrics`                       | `LiveBarEngine.ch_writer_metrics()` Arc reference         | VERIFIED | Lines 163-164: `engine.ch_writer_metrics().cloned()`; lines 572-598: merged into HashMap                           |
| `stream_manager_bindings.rs get_metrics()` | `stream_manager.rs get_combined_metrics()` | Existing PyDict conversion                                | VERIFIED | Bindings line 555: `manager.get_combined_metrics()` — entire HashMap exposed to Python, no changes needed          |

---

### Data-Flow Trace (Level 4)

These artifacts are Rust metrics aggregators, not components rendering dynamic user-visible data. No separate data-flow trace required — the wiring verification above confirms metrics flow from AtomicU64 counters through the HashMap to Python dict.

---

### Behavioral Spot-Checks

| Behavior                                   | Command                                                                                          | Result                                     | Status |
| ------------------------------------------ | ------------------------------------------------------------------------------------------------ | ------------------------------------------ | ------ |
| Guard tests pass (timestamp + volume)      | `cargo nextest run --features clickhouse-sink -E 'test(guard)'`                                  | 6/6 PASS                                   | PASS   |
| Fan-out test passes (counting sink)        | `cargo nextest run --features clickhouse-sink -E 'test(fan_out) or test(processor_fan_out)'`     | 2/2 PASS                                   | PASS   |
| Metrics keys present/absent correctly      | `cargo nextest run --features clickhouse-sink -E 'test(combined_metrics)'`                       | 3/3 PASS (including 2 `ch_writer_*` tests) | PASS   |
| No-feature build compiles cleanly          | `cargo build -p opendeviationbar-streaming --features binance-integration --no-default-features` | `Finished` 0.13s                           | PASS   |
| Total test count (clickhouse-sink enabled) | 12 tests matched across guard/fan_out/combined_metrics categories                                | 12/12 PASS                                 | PASS   |

---

### Requirements Coverage

| Requirement | Source Plan | Description                                                                | Status    | Evidence                                                                                         |
| ----------- | ----------- | -------------------------------------------------------------------------- | --------- | ------------------------------------------------------------------------------------------------ |
| INTEG-01    | 36-01       | Fan-out in LiveBarEngine — ClickHouseWriterSink runs alongside ChannelSink | SATISFIED | `dispatch_to_sinks()` called from trade_dispatch, puck, and fill_from_rest paths                 |
| INTEG-02    | 36-01       | Configuration via environment variables (`OPENDEVIATIONBAR_CH_HOSTS`)      | SATISFIED | `mod.rs` lines 146-148: `std::env::var("OPENDEVIATIONBAR_CH_HOSTS")` gates sink creation         |
| INTEG-04    | 36-02       | Metrics bridge to Python via StreamManager get_metrics() dict              | SATISFIED | 6 `ch_writer_*` keys in `get_combined_metrics()`; PyO3 bridge auto-exposes them                  |
| INTEG-05    | 36-01       | Pre-write guards: timestamp range + volume non-negative                    | SATISFIED | `validate_bar_for_write()` in guards.rs; called from `dispatch_to_sinks()` at all emission sites |
| INTEG-07    | 36-01       | Ouroboros mode hardcoded to "aion" in ClickHouseBarRow                     | SATISFIED | `row.rs`: `ouroboros_mode: "aion".to_string()` — completed in Phase 34, confirmed present        |

**Orphaned requirements check:** INTEG-03 (Phase 37, Pending) and INTEG-06 (Phase 38, Pending) are correctly assigned to future phases. No requirements were orphaned from Phase 36.

---

### Anti-Patterns Found

No anti-patterns detected in key files. Grep for TODO/FIXME/PLACEHOLDER/placeholder across all 4 key files returned no matches. No stub implementations, no hardcoded empty returns.

---

### Human Verification Required

None. All phase deliverables are verifiable programmatically via code inspection and test execution.

---

## Gaps Summary

No gaps. All 9 observable truths verified, all 7 artifacts substantive and wired, all 5 key links confirmed, all 5 requirement IDs satisfied, 12/12 tests pass, dual-feature-flag build verified.

---

_Verified: 2026-03-29T12:00:00Z_
_Verifier: Claude (gsd-verifier)_
