---
phase: 12-redis-backend
verified: 2026-02-23T22:10:00Z
status: passed
score: 12/12 must-haves verified
---

# Phase 12: Redis Backend Verification Report

**Phase Goal:** Developers can persist tasks in Redis for long-running server deployments by enabling the `redis` feature flag, proving the StorageBackend trait generalizes beyond DynamoDB
**Verified:** 2026-02-23T22:10:00Z
**Status:** passed
**Re-verification:** No — initial verification

---

## Goal Achievement

### Observable Truths (Plan 12-01)

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 1 | RedisBackend compiles behind the `redis` feature flag without affecting default builds | VERIFIED | `cargo check -p pmcp-tasks --features redis` passes; `cargo check -p pmcp-tasks` (no redis) also passes cleanly |
| 2 | Tasks stored in Redis use hash-based storage with version, data, and expires_at as separate hash fields | VERIFIED | `get()` reads `HGETALL` and extracts `version`, `data`, `expires_at` fields; Lua scripts `HSET` all three fields |
| 3 | All write operations (put, put_if_version, delete) are atomic via Lua scripts that update hash + sorted set + TTL in a single round-trip | VERIFIED | `LUA_PUT`, `LUA_PUT_IF_VERSION`, `LUA_DELETE` constants defined at lines 62, 92, 125; all three used via `Script::new(...)` in put (411), put_if_version (446), delete (481) |
| 4 | Expired tasks are filtered out during get and list_by_prefix via application-level expires_at check | VERIFIED | `is_expired()` called at line 371 in `get()` and line 528 in `list_by_prefix()` |
| 5 | Owner-scoped listing uses per-owner sorted set indexes | VERIFIED | `index_key()` at line 279 generates `{prefix}:idx:{owner_id}`; ZADD NX in both Lua PUT scripts; ZRANGE in `list_by_prefix()` at line 504 |
| 6 | cleanup_expired is a no-op returning Ok(0) | VERIFIED | Lines 564-565: `async fn cleanup_expired() -> Result<usize, StorageError> { Ok(0) }` |

### Observable Truths (Plan 12-02)

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 7 | All 6 StorageBackend methods are tested against a real Redis instance | VERIFIED | 19 `async fn redis_*` test functions covering get (2), put (3), put_if_version (4), delete (3), list_by_prefix (3), cleanup_expired (1), TTL (3) |
| 8 | Tests are gated behind the redis-tests feature flag and do not run by default | VERIFIED | `#[cfg(all(test, feature = "redis-tests"))]` at line 586; `cargo test -p pmcp-tasks` runs 76 tests, none from integration_tests module |
| 9 | Each test run is isolated via unique key prefix (no interference between test runs) | VERIFIED | `test_backend()` at line 592 generates `format!("test-{}", uuid::Uuid::new_v4())` prefix per call |
| 10 | TTL tests verify both EXPIREAT-based Redis auto-deletion setup and application-level filtering | VERIFIED | `redis_get_filters_expired_task` (past expiresAt, get returns NotFound); `redis_put_sets_ttl_when_expires_at_present` (HGETALL checks expires_at field); `redis_put_omits_expires_at_when_no_ttl` |
| 11 | CAS tests verify atomic version checking and VersionConflict error on mismatch | VERIFIED | `redis_put_if_version_fails_on_mismatch` and `redis_put_if_version_fails_on_missing_key` assert `StorageError::VersionConflict` |
| 12 | Sorted set index tests verify owner-scoped listing returns correct tasks | VERIFIED | `redis_list_by_prefix_returns_matching` creates tasks for two owners, asserts listing owner-a returns only 2 owner-a tasks |

**Score:** 12/12 truths verified

---

## Required Artifacts

| Artifact | Expected | Status | Details |
|----------|----------|--------|---------|
| `crates/pmcp-tasks/src/store/redis.rs` | RedisBackend struct implementing StorageBackend with all 6 methods, min 200 lines | VERIFIED | 912 lines; `impl StorageBackend for RedisBackend` at line 353 with all 6 methods |
| `crates/pmcp-tasks/Cargo.toml` | redis and redis-tests feature flags with optional redis dependency | VERIFIED | Line 23: `redis = { version = "1.0", features = ["tokio-comp", "script"], optional = true }`; Lines 28-29: `redis = ["dep:redis"]` and `redis-tests = ["redis"]` |
| `crates/pmcp-tasks/src/store/mod.rs` | Conditional redis module declaration | VERIFIED | Lines 43-44: `#[cfg(feature = "redis")] pub mod redis;` |
| `crates/pmcp-tasks/src/lib.rs` | Conditional RedisBackend re-export | VERIFIED | Lines 59-60: `#[cfg(feature = "redis")] pub use store::redis::RedisBackend;` |

---

## Key Link Verification

| From | To | Via | Status | Details |
|------|----|-----|--------|---------|
| `crates/pmcp-tasks/src/store/redis.rs` | `crates/pmcp-tasks/src/store/backend.rs` | `impl StorageBackend for RedisBackend` | VERIFIED | Pattern found at line 353 |
| `crates/pmcp-tasks/src/store/mod.rs` | `crates/pmcp-tasks/src/store/redis.rs` | feature-gated module declaration | VERIFIED | `#[cfg(feature = "redis")] pub mod redis;` at lines 43-44 |
| `crates/pmcp-tasks/src/lib.rs` | `crates/pmcp-tasks/src/store/redis.rs` | conditional re-export | VERIFIED | `#[cfg(feature = "redis")] pub use store::redis::RedisBackend;` at lines 59-60 |
| `integration_tests mod` | `RedisBackend` | `test_backend()` helper | VERIFIED | `async fn test_backend()` at line 592 creates isolated RedisBackend |
| `integration_tests mod` | `StorageBackend trait` | direct method calls | VERIFIED | All 6 methods called directly: get, put, put_if_version, delete, list_by_prefix, cleanup_expired |

---

## Requirements Coverage

| Requirement | Source Plan | Description | Status | Evidence |
|-------------|------------|-------------|--------|----------|
| RDIS-01 | 12-01 | RedisBackend implements StorageBackend behind `redis` feature flag | SATISFIED | `impl StorageBackend for RedisBackend` at line 353; compiles with `--features redis`, clean without |
| RDIS-02 | 12-01 | Hash-based storage mapping task record fields to Redis hash fields | SATISFIED | HSET stores `version`, `data`, `expires_at` fields; HGETALL retrieves them in `get()` |
| RDIS-03 | 12-01 | Lua scripts for atomic check-and-set operations | SATISFIED | LUA_PUT, LUA_PUT_IF_VERSION, LUA_DELETE — each updates hash + sorted set + TTL in a single EVAL |
| RDIS-04 | 12-01 | EXPIRE-based TTL with application-level enforcement | SATISFIED | EXPIREAT set in Lua scripts; `is_expired()` provides app-level check in get and list_by_prefix |
| RDIS-05 | 12-01 | Sorted set indexing for owner-scoped task listing | SATISFIED | `{prefix}:idx:{owner_id}` sorted sets; ZADD NX in writes; ZRANGE in list_by_prefix; lazy ZREM for orphans |
| TEST-03 | 12-02 | Per-backend integration tests for RedisBackend against Redis instance | SATISFIED | 19 tests in `integration_tests` module gated behind `redis-tests` feature; covers all 6 StorageBackend methods |

All 6 requirement IDs declared in plan frontmatter are accounted for. No orphaned requirements found — REQUIREMENTS.md maps all 6 to Phase 12 and marks them Complete.

---

## Anti-Patterns Found

No anti-patterns detected.

Scanned `crates/pmcp-tasks/src/store/redis.rs` (912 lines) for:
- TODO/FIXME/XXX/HACK/PLACEHOLDER: None
- Empty implementations (`return null`, `return {}`, `return []`): None (cleanup_expired returns `Ok(0)` which is the documented no-op behavior, not a stub)
- Console.log only implementations: Not applicable (Rust)
- Unimplemented stubs: None

---

## Human Verification Required

### 1. Redis Integration Tests Against Live Redis

**Test:** `cargo test -p pmcp-tasks --features redis-tests -- redis_ --test-threads=1` against a running Redis instance
**Expected:** All 19 tests pass
**Why human:** Requires a Redis instance running on localhost:6379 (or REDIS_URL env var). Cannot verify without a live Redis server. Tests validate actual wire protocol behavior: Lua script execution, hash storage, sorted set indexing, TTL semantics.

---

## Build Verification Summary

All automated compilation and quality checks passed:

| Check | Command | Result |
|-------|---------|--------|
| Redis feature compiles | `cargo check -p pmcp-tasks --features redis` | PASSED |
| Default build unaffected | `cargo check -p pmcp-tasks` | PASSED |
| Both backends together | `cargo check -p pmcp-tasks --features dynamodb,redis` | PASSED |
| Zero clippy warnings | `cargo clippy -p pmcp-tasks --features redis -- -D warnings` | PASSED |
| Clean formatting | `cargo fmt -p pmcp-tasks --check` | PASSED |
| Existing tests (76) | `cargo test -p pmcp-tasks` | PASSED (76 passed, 0 failed) |

Commits verified in git history:
- `e97559a` — `feat(12-01): implement RedisBackend with StorageBackend trait behind redis feature flag`
- `a0074aa` — `test(12-02): add redis_get_filters_expired_task integration test`

---

## Gaps Summary

No gaps. All must-haves verified, all artifacts exist and are substantive (912 lines, not stubs), all key links are wired, all 6 requirement IDs are satisfied, and zero anti-patterns found.

The only item deferred to human verification is running the integration test suite against a live Redis instance — all automated checks pass.

---

_Verified: 2026-02-23T22:10:00Z_
_Verifier: Claude (gsd-verifier)_
