---
phase: 11-dynamodb-backend
verified: 2026-02-23T12:00:00Z
status: passed
score: 11/11 must-haves verified
re_verification: false
gaps: []
human_verification:
  - test: "Run DynamoDB integration tests against real AWS infrastructure"
    expected: "All 18 ddb_ tests pass when run with: cargo test -p pmcp-tasks --features dynamodb-tests -- ddb_ --test-threads=1"
    why_human: "Requires live AWS credentials and a provisioned DynamoDB table. Cannot verify cloud connectivity or real DynamoDB behavior programmatically."
---

# Phase 11: DynamoDB Backend Verification Report

**Phase Goal:** Developers can persist tasks in DynamoDB for production AWS/Lambda deployments by enabling the `dynamodb` feature flag
**Verified:** 2026-02-23T12:00:00Z
**Status:** passed
**Re-verification:** No — initial verification

## Goal Achievement

### Observable Truths (from PLAN 11-01 must_haves)

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 1 | DynamoDbBackend compiles behind the `dynamodb` feature flag | VERIFIED | `cargo check -p pmcp-tasks --features dynamodb` exits 0; `DynamoDbBackend` struct at line 95 of `dynamodb.rs` |
| 2 | Crate compiles without `dynamodb` feature (no aws-sdk-dynamodb dependency pulled in) | VERIFIED | `cargo check -p pmcp-tasks` exits 0; aws-sdk-dynamodb is `optional = true` in Cargo.toml |
| 3 | DynamoDbBackend implements all 6 StorageBackend methods | VERIFIED | `impl StorageBackend for DynamoDbBackend` at line 241; all 6 methods present: `get`, `put`, `put_if_version`, `delete`, `list_by_prefix`, `cleanup_expired` |
| 4 | put_if_version uses ConditionExpression for atomic CAS | VERIFIED | Lines 336-341: `.condition_expression("#v = :expected")` with `expression_attribute_names` and `expression_attribute_values` set |
| 5 | cleanup_expired is a no-op returning Ok(0) | VERIFIED | Lines 452-454: `async fn cleanup_expired() -> Result<usize, StorageError> { Ok(0) }` with doc comment explaining DynamoDB native TTL |
| 6 | TTL epoch seconds extracted from data and stored as expires_at attribute only when present | VERIFIED | Lines 306-308 (put) and 343-345 (put_if_version): `if let Some(epoch) = extract_ttl_epoch(data) { builder = builder.item("expires_at", ...) }` — omitted when None |

### Observable Truths (from PLAN 11-02 must_haves)

| # | Truth | Status | Evidence |
|---|-------|--------|----------|
| 7 | Integration tests exercise all 6 StorageBackend methods against real DynamoDB | VERIFIED | 18 tests at lines 517-818 covering get(2), put(3), put_if_version(4), delete(3), list_by_prefix(3), cleanup_expired(1), TTL(2) |
| 8 | Tests are gated behind dynamodb-tests feature flag and do not run by default | VERIFIED | `#[cfg(all(test, feature = "dynamodb-tests"))] mod integration_tests` at line 500; `cargo test -p pmcp-tasks` runs 561 tests with no DynamoDB tests |
| 9 | Each test run uses a unique owner prefix for isolation (no table cleanup needed) | VERIFIED | `test_backend()` at line 509-513: `format!("test-{}", uuid::Uuid::new_v4())` generates unique UUID per test invocation |
| 10 | TTL verification checks expires_at attribute is set correctly on items (does not wait for actual deletion) | VERIFIED | `ddb_put_sets_expires_at_attribute_when_ttl_present` (line 747) and `ddb_put_omits_expires_at_when_no_ttl` (line 790) use raw `GetItem` to inspect attributes |
| 11 | CAS conflict test verifies VersionConflict error on version mismatch | VERIFIED | `ddb_put_if_version_fails_on_mismatch` (line 587) asserts `StorageError::VersionConflict` with correct key and expected version |

**Score:** 11/11 truths verified

### Required Artifacts

| Artifact | Expected | Status | Details |
|----------|----------|--------|---------|
| `crates/pmcp-tasks/Cargo.toml` | dynamodb and dynamodb-tests feature flags with optional aws-sdk-dynamodb and aws-config deps | VERIFIED | Lines 21-26: `aws-sdk-dynamodb = { version = "1", optional = true }`, `aws-config = { version = "1", features = ["behavior-version-latest"], optional = true }`, `[features]` with `dynamodb` and `dynamodb-tests` |
| `crates/pmcp-tasks/src/store/dynamodb.rs` | DynamoDbBackend struct implementing StorageBackend; min 150 lines | VERIFIED | 819 lines total; struct at line 95; `impl StorageBackend` at line 241; all 6 methods substantive |
| `crates/pmcp-tasks/src/store/mod.rs` | Conditional dynamodb module declaration containing `cfg(feature` | VERIFIED | Lines 37-38: `#[cfg(feature = "dynamodb")] pub mod dynamodb;` |
| `crates/pmcp-tasks/src/lib.rs` | Conditional DynamoDbBackend re-export | VERIFIED | Lines 54-55: `#[cfg(feature = "dynamodb")] pub use store::dynamodb::DynamoDbBackend;` |

### Key Link Verification

| From | To | Via | Status | Details |
|------|----|-----|--------|---------|
| `dynamodb.rs` | `store/backend.rs` | `impl StorageBackend for DynamoDbBackend` | WIRED | Line 241: `impl StorageBackend for DynamoDbBackend`; all 6 trait methods implemented with real logic |
| `dynamodb.rs` | `aws-sdk-dynamodb` | DynamoDB Client API calls | WIRED | Lines 60-61: `use aws_sdk_dynamodb::types::AttributeValue; use aws_sdk_dynamodb::Client;`; all methods call real DynamoDB API |
| `store/mod.rs` | `store/dynamodb.rs` | conditional module declaration | WIRED | Lines 37-38: `#[cfg(feature = "dynamodb")] pub mod dynamodb;` — correct cfg pattern |
| `integration_tests` | `DynamoDbBackend` | StorageBackend trait method calls | WIRED | 18 test functions calling `backend.get`, `backend.put`, `backend.put_if_version`, `backend.delete`, `backend.list_by_prefix`, `backend.cleanup_expired` |
| `integration_tests` | AWS DynamoDB | `from_env()` constructor using AWS SDK config chain | WIRED | Line 510: `DynamoDbBackend::from_env().await` in `test_backend()` helper |

### Requirements Coverage

| Requirement | Source Plan | Description | Status | Evidence |
|-------------|-------------|-------------|--------|----------|
| DYNA-01 | 11-01-PLAN.md | DynamoDbBackend implements StorageBackend behind `dynamodb` feature flag | SATISFIED | Feature flag compiles; `impl StorageBackend for DynamoDbBackend` verified |
| DYNA-02 | 11-01-PLAN.md | Single-table design with composite keys for task storage and owner isolation | SATISFIED | `make_pk`/`make_sk` helpers produce `OWNER#<id>`/`TASK#<id>` keys; Query-based isolation in `list_by_prefix` |
| DYNA-03 | 11-01-PLAN.md | ConditionExpression for atomic state transitions (concurrent mutation safety) | SATISFIED | `put_if_version` uses `.condition_expression("#v = :expected")` with `ConditionalCheckFailedException` mapped to `VersionConflict` |
| DYNA-04 | 11-01-PLAN.md | Native DynamoDB TTL for automatic expired task cleanup | SATISFIED | `extract_ttl_epoch` parses `expiresAt` from JSON; `expires_at` attribute set as Number in epoch seconds; `cleanup_expired` is no-op relying on DynamoDB native TTL |
| DYNA-05 | 11-01-PLAN.md | Automatic variable size cap at ~350KB to stay within DynamoDB's 400KB item limit | SATISFIED | Doc comment on struct (lines 77-82) explains size enforcement is in `GenericTaskStore::StoreConfig::max_variable_size_bytes`; backend never sees oversized items |
| DYNA-06 | 11-02-PLAN.md | Cloud-only integration tests against real DynamoDB table | SATISFIED | 18 integration tests in `dynamodb.rs` gated behind `dynamodb-tests` feature; tests require AWS credentials at runtime |
| TEST-02 | 11-02-PLAN.md | Per-backend integration tests for DynamoDbBackend against cloud DynamoDB | SATISFIED | 18 `ddb_` prefixed tests covering all 6 StorageBackend contract methods; UUID-based isolation; TTL attribute verification |

**Orphaned requirements check:** REQUIREMENTS.md maps DYNA-01 through DYNA-06 and TEST-02 to Phase 11. All 7 requirement IDs appear in plan frontmatter. No orphaned requirements.

### Anti-Patterns Found

| File | Line | Pattern | Severity | Impact |
|------|------|---------|----------|--------|
| — | — | No anti-patterns detected | — | — |

Scan results:
- Zero TODO/FIXME/HACK/PLACEHOLDER comments in `dynamodb.rs`
- No `return null`, `return {}`, `return []` stubs — all methods have substantive implementations
- `cleanup_expired` returns `Ok(0)` intentionally (no-op per design; documented with rationale)
- No console-log-only implementations
- Clippy: zero warnings with `--features dynamodb` and `--features dynamodb-tests --tests`
- Formatting: `cargo fmt --check` passes cleanly

### Doc Warnings (Pre-existing, Out of Phase Scope)

`cargo doc -p pmcp-tasks --features dynamodb --no-deps` produces 5 warnings:
- `unresolved link to 'SequentialWorkflow'` (in `workflow.rs`)
- `unresolved link to 'WorkflowStep'` (in `workflow.rs`)
- `unresolved link to 'generic::GenericTaskStore'`
- `unresolved link to 'WorkflowProgress'`
- `unresolved link to 'WORKFLOW_PROGRESS_KEY'`

These warnings are in pre-existing workflow-related files (`workflow.rs`, `router.rs`) not touched by Phase 11. The 11-02-SUMMARY.md documents these as pre-existing out-of-scope issues.

### Human Verification Required

#### 1. DynamoDB Integration Tests Against Real AWS

**Test:** With valid AWS credentials and a `pmcp_tasks` DynamoDB table (PK=String, SK=String, TTL attribute=`expires_at`), run:
```bash
cargo test -p pmcp-tasks --features dynamodb-tests -- ddb_ --test-threads=1
```
**Expected:** All 18 `ddb_` tests pass. `ddb_put_sets_expires_at_attribute_when_ttl_present` verifies epoch value is within 2 hours of now.
**Why human:** Requires live AWS credentials and provisioned DynamoDB infrastructure. Cannot be verified programmatically without cloud access.

## Quality Gates

| Check | Command | Result |
|-------|---------|--------|
| Compile without feature | `cargo check -p pmcp-tasks` | PASS |
| Compile with dynamodb | `cargo check -p pmcp-tasks --features dynamodb` | PASS |
| Compile with dynamodb-tests | `cargo check -p pmcp-tasks --features dynamodb-tests` | PASS |
| Clippy (dynamodb) | `cargo clippy -p pmcp-tasks --features dynamodb -- -D warnings` | PASS (zero warnings) |
| Clippy (dynamodb-tests + tests) | `cargo clippy -p pmcp-tasks --features dynamodb-tests --tests -- -D warnings` | PASS (zero warnings) |
| Formatting | `cargo fmt -p pmcp-tasks --check` | PASS |
| Existing tests | `cargo test -p pmcp-tasks` | PASS (561 tests, 0 failed) |
| Commits | 757c8f9 (feat), eafdff4 (test), efab375 (chore) | All present in git log |

## Gaps Summary

No gaps. All 11 must-have truths verified. All 7 requirement IDs (DYNA-01 through DYNA-06, TEST-02) satisfied with implementation evidence. No anti-patterns or stubs detected.

The one item requiring human verification (running integration tests against real AWS) is expected by design — the tests require cloud infrastructure and AWS credentials that cannot be provisioned programmatically during verification.

---

_Verified: 2026-02-23T12:00:00Z_
_Verifier: Claude (gsd-verifier)_
