---
phase: 08-checksum-spike
verified: 2026-03-26T05:15:00Z
status: passed
score: 8/8 must-haves verified
re_verification: false
gaps: []
human_verification:
  - test: "Run full network integration script"
    expected: "SPIKE-01 PASS (real Vision data), SPIKE-02 PASS (overhead noted at 13.5%, user-approved), SPIKE-03 PASS (all 4 edge cases)"
    why_human: "Network script requires live Binance Vision connectivity; user already ran and approved (see SUMMARY key-decisions). Cannot re-run without network access to data.binance.vision."
---

# Phase 8: Checksum Spike Verification Report

**Phase Goal:** Rust checksum.rs SHA-256 fetch+verify is proven callable from Python with correct results, acceptable performance, and graceful edge case handling
**Verified:** 2026-03-26T05:15:00Z
**Status:** passed
**Re-verification:** No — initial verification

## Goal Achievement

### Observable Truths

| #   | Truth                                                                                             | Status     | Evidence                                                                                                                     |
| --- | ------------------------------------------------------------------------------------------------- | ---------- | ---------------------------------------------------------------------------------------------------------------------------- |
| 1   | Python can call compute_sha256_hex() and get a correct 64-char lowercase hex hash                 | VERIFIED   | Import confirmed; `compute_sha256_hex(b"hello world")` returns known hash                                                    |
| 2   | Python can call verify_checksum_hex() and get a dict with verified/expected/actual/skipped fields | VERIFIED   | Import confirmed; dict with all 4 keys returned; verified=True, skipped=False                                                |
| 3   | Python can call parse_checksum_file_content() and extract the hash from Binance CHECKSUM format   | VERIFIED   | Import confirmed; parses `hash  filename` format correctly                                                                   |
| 4   | A real Vision ZIP download verified against its .CHECKSUM file produces verified=true             | VERIFIED   | SPIKE-01 user-approved; network script passed; SUMMARY confirms 2024-01-01 BTCUSDT verified                                  |
| 5   | Checksum verification adds less than 10% wall-clock overhead to a Vision download cycle           | VERIFIED\* | SPIKE-02 measured 13.5% — user explicitly approved as acceptable for background seeder workload                              |
| 6   | A 404 CHECKSUM (old data) results in skipped=true, not a crash                                    | VERIFIED   | SPIKE-03 edge case 3a; user-approved; integrated path soft-skips on non-mismatch RuntimeError                                |
| 7   | A corrupted download (wrong hash) results in a RuntimeError with 'mismatch' in the message        | VERIFIED   | Programmatically confirmed: `verify_checksum_hex(b"test", "a"*64)` raises `RuntimeError: Checksum mismatch: expected aaa...` |
| 8   | A network timeout on CHECKSUM fetch results in skipped=true, not a crash                          | VERIFIED   | SPIKE-03 edge case 3d; user-approved; Rust `fetch_and_verify` returns `ChecksumResult::skipped()` on FetchFailed             |

\*Truth 5 deviation: 13.5% vs 10% nominal threshold. User explicitly approved this deviation; bottleneck is HTTP round-trip for 98-byte .CHECKSUM file, not SHA-256 computation. Treated as passed per user instruction.

**Score:** 8/8 truths verified

### Required Artifacts

| Artifact                               | Expected                                                                                       | Status   | Details                                                                                    |
| -------------------------------------- | ---------------------------------------------------------------------------------------------- | -------- | ------------------------------------------------------------------------------------------ |
| `src/binance_bindings.rs`              | Three new PyO3 functions: compute_sha256_hex, verify_checksum_hex, parse_checksum_file_content | VERIFIED | Lines 62-127: all three functions present and substantive                                  |
| `src/lib.rs`                           | Registration of three new checksum functions in \_core module                                  | VERIFIED | Lines 149-161: all three registered under data-providers feature gate with Phase 8 comment |
| `tests/test_checksum_spike.py`         | Offline unit tests for new PyO3 checksum bindings                                              | VERIFIED | 11 test methods across 3 test classes; all pass (`pytest ... -x -q` exits 0)               |
| `scripts/spike_checksum_validation.py` | Network integration test: SPIKE-01/02/03 validation                                            | VERIFIED | All 4 sections present (preflight, SPIKE-01, SPIKE-02, SPIKE-03); sys.exit(0/1) wired      |

### Key Link Verification

| From                                   | To                                                          | Via                                                                                                       | Status | Details                                                                                                                            |
| -------------------------------------- | ----------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | ------ | ---------------------------------------------------------------------------------------------------------------------------------- |
| `src/binance_bindings.rs`              | `crates/opendeviationbar-providers/src/binance/checksum.rs` | `use opendeviationbar_providers::binance::checksum`                                                       | WIRED  | Line 4 of binance_bindings.rs; `checksum::compute_sha256`, `checksum::verify_checksum`, `checksum::parse_checksum_file` all called |
| `tests/test_checksum_spike.py`         | `src/binance_bindings.rs` (compiled into `_core`)           | `from opendeviationbar._core import compute_sha256_hex`                                                   | WIRED  | All three functions imported at line 10-14; all used in tests                                                                      |
| `scripts/spike_checksum_validation.py` | `src/binance_bindings.rs` (compiled into `_core`)           | `from opendeviationbar._core import compute_sha256_hex, verify_checksum_hex, parse_checksum_file_content` | WIRED  | All three imported at lines 19-24; all used across sections                                                                        |

### Data-Flow Trace (Level 4)

| Artifact                      | Data Variable | Source                                                         | Produces Real Data                | Status  |
| ----------------------------- | ------------- | -------------------------------------------------------------- | --------------------------------- | ------- |
| `compute_sha256_hex`          | Return string | `checksum::compute_sha256(data)` (Rust sha2 crate)             | Yes — hashes input bytes          | FLOWING |
| `verify_checksum_hex`         | Return dict   | `checksum::verify_checksum(data, expected)` → `ChecksumResult` | Yes — computes and compares       | FLOWING |
| `parse_checksum_file_content` | Return string | `checksum::parse_checksum_file(content)` → parsed hash         | Yes — parses real CHECKSUM format | FLOWING |

### Behavioral Spot-Checks

| Behavior                                             | Command                                                          | Result                                                                       | Status |
| ---------------------------------------------------- | ---------------------------------------------------------------- | ---------------------------------------------------------------------------- | ------ |
| `compute_sha256_hex(b"hello world")` = known hash    | Python import + assert                                           | `b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9` — correct | PASS   |
| `verify_checksum_hex` returns correct dict structure | Python import + assert all 4 keys, verified=True, skipped=False  | All keys present, values correct                                             | PASS   |
| Mismatch raises RuntimeError with "mismatch"         | `verify_checksum_hex(b"test", "a"*64)` → catch RuntimeError      | `RuntimeError: Checksum mismatch: expected aaa...` — message confirmed       | PASS   |
| Empty content raises ValueError                      | `parse_checksum_file_content("")` → catch ValueError             | ValueError raised immediately                                                | PASS   |
| Offline test suite (11 tests)                        | `uv run --python 3.13 pytest tests/test_checksum_spike.py -x -q` | `...........` — 11 passed, exit 0                                            | PASS   |
| Both commits exist in git                            | `git log --oneline 4bc4147 18fd6c6`                              | Both hashes resolve to correct feat/test commits                             | PASS   |

### Requirements Coverage

| Requirement | Source Plan | Description                                                                                                    | Status      | Evidence                                                                                                             |
| ----------- | ----------- | -------------------------------------------------------------------------------------------------------------- | ----------- | -------------------------------------------------------------------------------------------------------------------- |
| SPIKE-01    | 08-01-PLAN  | Rust checksum.rs SHA-256 fetch+verify callable from Python, correct results against real Vision CHECKSUM files | SATISFIED   | All 3 PyO3 functions importable; known hash correct; offline tests pass; user ran network script                     |
| SPIKE-02    | 08-01-PLAN  | Performance overhead of checksum verification measured (< 10% wall-clock increase acceptable)                  | SATISFIED\* | 13.5% measured; user approved as acceptable for background seeder; documented in SUMMARY key-decisions               |
| SPIKE-03    | 08-01-PLAN  | Edge cases: 404=soft-skip, timeout=soft-skip, mismatch=hard-fail, invalid-format=hard-fail                     | SATISFIED   | 3b (mismatch) and 3c (invalid) verified programmatically; 3a (404) and 3d (timeout) user-verified via network script |

\*SPIKE-02 deviation noted and approved per user instruction before this verification.

**Orphaned requirements check:** REQUIREMENTS.md traceability table lists SPIKE-01/02/03 as "Phase 8" with status "Pending" (lines 37-39) — this conflicts with the `[x]` checkboxes at lines 10-12 marking them complete. The code is fully implemented; the traceability table status field was not updated after completion. This is a documentation inconsistency only, not a code gap.

No REQUIREMENTS.md phase-8 requirements are orphaned from the plan.

### Anti-Patterns Found

| File                                   | Line | Pattern                                                                  | Severity | Impact                                                                                                                                                                                                                         |
| -------------------------------------- | ---- | ------------------------------------------------------------------------ | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `scripts/spike_checksum_validation.py` | 186  | `zip_bytes` reference in Section 3b may be undefined if Section 1 failed | Info     | Section 3b uses `zip_bytes` captured in Section 1; if Section 1 raises an exception mid-way (before `zip_bytes` is assigned), Section 3b would raise NameError. Acceptable for a spike validation script; not production code. |

No blockers or warnings found. The single Info-level pattern is benign in a spike script context.

### Human Verification Required

#### 1. SPIKE-02 Performance Overhead

**Test:** Run `uv run --python 3.13 python scripts/spike_checksum_validation.py` on a machine with network access to `data.binance.vision`
**Expected:** SPIKE-02 section reports overhead measurement (user observed 13.5% during Phase 8 execution, approved as acceptable)
**Why human:** Network connectivity to Binance Vision required; overhead depends on network conditions; user already ran and approved this during execution checkpoint

#### 2. SPIKE-01 Real Vision Data Verification

**Test:** Run `uv run --python 3.13 python scripts/spike_checksum_validation.py` — Section 1 downloads BTCUSDT-aggTrades-2024-01-01.zip and its .CHECKSUM
**Expected:** `SPIKE-01 PASS: SHA-256 verified for BTCUSDT 2024-01-01 (N bytes)`
**Why human:** Live network download required; user confirmed during Task 3 human-verify checkpoint

### Gaps Summary

No gaps. All 8 must-have truths are verified. All 4 artifacts exist, are substantive, and are wired. All 3 key links confirmed. All 3 SPIKE requirements satisfied (SPIKE-02 with user-approved deviation documented in SUMMARY).

The REQUIREMENTS.md traceability table has a stale "Pending" status for SPIKE-01/02/03 — this is a documentation issue, not a code gap. The `[x]` checkboxes at lines 10-12 correctly reflect completion.

---

_Verified: 2026-03-26T05:15:00Z_
_Verifier: Claude (gsd-verifier)_
