# Code Review Process

This document describes how to perform a comprehensive, per-module code review of
the `lmxopcua` codebase (the ZB.MOM.WW.OtOpcUa OPC UA server) and how to track
findings to resolution.

A **module** is one buildable project under `src/` (e.g.
`src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy`) or one test project under `tests/`
(e.g. `tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests`). Each module has its
own folder under `code-reviews/` containing a single `findings.md`.

## 1. Before you start

1. Pick the module to review. Its folder is `code-reviews/<Module>/`, where
   `<Module>` is the project name with the `ZB.MOM.WW.OtOpcUa.` prefix stripped:
   - `src/Server/ZB.MOM.WW.OtOpcUa.Server` is reviewed in `code-reviews/Server/`.
   - `src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy` → `code-reviews/Driver.Galaxy/`.
   - `src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions` → `code-reviews/Core.Abstractions/`.
   - `tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests` →
     `code-reviews/Driver.Galaxy.Tests/`.

   The solution `ZB.MOM.WW.OtOpcUa.slnx` enumerates every project; `src/` is
   grouped into `Core/`, `Server/`, `Drivers/`, `Client/`, and `Tooling/`.
2. Identify the design context for the module:
   - `CLAUDE.md` — project goal, the data-flow architecture, the contained-name
     vs tag-name concept, and the **Library Preferences** / build & runtime
     constraints.
   - `StyleGuide.md` — repository code-style conventions.
   - The relevant docs under `docs/` and `docs/v2/` — e.g. `docs/OpcUaServer.md`,
     `docs/AddressSpace.md`, `docs/ReadWriteOperations.md`, `docs/security.md`,
     `docs/Redundancy.md`, `docs/ScriptedAlarms.md`, `docs/AlarmTracking.md`,
     `docs/ServiceHosting.md`, `docs/v2/plan.md`, `docs/v2/acl-design.md`,
     `docs/v2/driver-specs.md`, `docs/v2/driver-stability.md`, the
     `docs/v2/Galaxy.*.md` set, and the driver notes under `docs/drivers/`.
   - The auto-memory index at
     `~/.claude/projects/.../memory/MEMORY.md` records non-obvious project
     decisions and is worth a scan before a review.
3. Record the exact commit being reviewed: `git rev-parse --short HEAD`. Every
   review is a snapshot — a finding only means something relative to a known
   commit.
4. Open `code-reviews/<Module>/findings.md` (copy it from
   [`code-reviews/_template/findings.md`](code-reviews/_template/findings.md) if it
   does not exist yet) and fill in the header table (reviewer, date, commit SHA,
   status).

## 2. Review checklist

Work through **every** category below for the module. A comprehensive review
means the checklist is completed even where it produces no findings — record
"No issues found" for a category rather than leaving it ambiguous.

1. **Correctness & logic bugs** — off-by-one, null handling, incorrect
   conditionals, misuse of APIs, broken edge cases, wrong data-type mapping.
2. **OtOpcUa conventions** — the rules in `CLAUDE.md` and `StyleGuide.md`: Galaxy
   access flows through the in-process `GalaxyDriver` over gRPC to the separately
   installed `mxaccessgw` gateway — nothing in this repo loads MXAccess COM
   directly; browse uses **contained names** and runtime read/write uses
   **tag names** (`tag_name.AttributeName`); authorization decisions happen in
   `DriverNodeManager` at the server layer, never in driver-level code — drivers
   only report `SecurityClassification` as metadata; .NET 10 / AnyCPU; Serilog
   with a rolling daily file sink; xUnit + Shouldly for unit tests; the .NET
   generic host with `AddWindowsService` for the Server and Admin hosts; the OPC
   Foundation UA .NET Standard stack for OPC UA; generated code is not
   hand-edited.
3. **Concurrency & thread safety** — shared mutable state, race conditions,
   correct use of `async`/`await`, locking, disposal races, background-loop and
   reconnect-supervisor lifetimes.
4. **Error handling & resilience** — exception paths, driver/gateway reconnect
   handling, transient vs permanent error classification, graceful degradation,
   correct OPC UA `StatusCode`s, address-space rebuild on redeploy.
5. **Security** — OPC UA transport security profiles (`SecurityProfileResolver`),
   LDAP bind authentication and the group→permission mapping
   (`LdapUserAuthenticator`), ACL enforcement at the `DriverNodeManager` layer,
   input validation, SQL injection in the `ConfigDb` / Galaxy Repository queries,
   certificate handling, and secret handling (no logging of credentials, LDAP
   service-account passwords, or API keys).
6. **Performance & resource management** — `IDisposable` disposal, gRPC channel /
   stream / session lifetimes, buffering and back-pressure on event pumps,
   unnecessary allocations on hot paths, N+1 queries.
7. **Design-document adherence** — does the code match `CLAUDE.md`, the relevant
   `docs/` and `docs/v2/` designs? Flag both code that drifts from the design and
   design docs that are now stale.
8. **Code organization & conventions** — namespace hierarchy, project layout, the
   Options pattern, separation of concerns, the capability-interface seams
   (`IReadable`, `IWritable`, `ISubscribable`, `IAlarmSource`, etc.).
9. **Testing coverage** — are the module's behaviours covered? Unit suites are
   `*.Tests` (xUnit + Shouldly); integration suites are `*.IntegrationTests` and
   need their Docker fixture up; DB-backed tests in `*.Configuration.Tests`,
   `*.Admin.Tests`, and `*.Server.Tests` need the central SQL Server. Note
   untested critical paths and missing edge-case tests.
10. **Documentation & comments** — XML doc accuracy, misleading or stale comments,
    undocumented non-obvious behaviour.

## 3. Recording findings

Add one entry per finding to the `## Findings` section of the module's
`findings.md`, using the entry format in
[`_template/findings.md`](code-reviews/_template/findings.md).

- **Finding ID** — `<Module>-NNN`, numbered sequentially within the module and
  never reused (e.g. `Driver.Galaxy-001`). IDs are permanent even after
  resolution.
- **Severity:**
  - **Critical** — data loss, security breach, crash/deadlock, or outage.
  - **High** — incorrect behaviour with significant impact; no safe workaround.
  - **Medium** — incorrect or risky behaviour with limited impact or a workaround.
  - **Low** — minor issues, style, maintainability, documentation.
- **Category** — one of the 10 checklist categories above.
- **Location** — `file:line` (clickable), or a list of locations.
- **Description** — what is wrong and why it matters.
- **Recommendation** — concrete suggested fix.

After recording findings, update the module header table (status, open-finding
count) and regenerate the base README (step 5).

## 4. Marking an item resolved

Findings are **never deleted** — they are an audit trail. To close one, change
its **Status** and complete the **Resolution** field:

- `Open` — newly recorded, not yet addressed.
- `In Progress` — a fix is actively being worked on.
- `Resolved` — fixed. The Resolution field must state the fixing commit SHA, the
  date, and a one-line description of the fix.
- `Won't Fix` — intentionally not fixed. The Resolution field must justify why.
- `Deferred` — valid but postponed. The Resolution field must say what it is
  waiting on (e.g. a tracked issue or a later milestone).

`Resolved`, `Won't Fix`, and `Deferred` findings are all considered **closed**.
`Open` and `In Progress` are **pending** and appear in the base README's Pending
Findings table.

## 5. Updating the base README

`code-reviews/README.md` holds the single cross-module view (the Module Status
table and the Pending / Closed Findings tables). It is **generated** from the
per-module `findings.md` files — do not edit it by hand.

After any review or status change, regenerate it:

```
python code-reviews/regen-readme.py
```

`regen-readme.py --check` exits non-zero if `README.md` is stale, if a module
header's `Open findings` count disagrees with its finding statuses, or if a
finding carries an unrecognised Status value. The PowerShell wrapper
`scripts/check-code-reviews-readme.ps1` runs that check and is the intended hook
for CI or a pre-commit step. `code-reviews/test_regen_readme.py` covers the
generator itself (`python code-reviews/test_regen_readme.py`).

> The repo's installed `python` is the real interpreter; the bare `python3`
> alias on this box resolves to the Windows Store stub and fails. Use `python`.

The per-module `findings.md` files are the source of truth; `README.md` is the
aggregated index and must always agree with them — which the script guarantees.

## 6. Re-reviewing a module

Re-reviews append to the same `findings.md`. Update the header to the new commit
and date, continue the finding numbering from the last used ID, and leave prior
findings (including closed ones) in place as history.