# Code Review Process

This document describes how to perform a comprehensive, per-module code review of
the ScadaLink codebase and how to track findings to resolution.

A **module** is one buildable project under `src/` (e.g. `src/ScadaLink.TemplateEngine`).
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 `ScadaLink.` prefix stripped.
2. Identify the design context for the module:
   - Its component design doc: `docs/requirements/Component-<Name>.md`.
   - The relevant **Key Design Decisions** in `CLAUDE.md`.
   - `docs/requirements/HighLevelReqs.md` for cross-cutting requirements.
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` and fill in the header table
   (reviewer, date, commit SHA).

## 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.
2. **Akka.NET conventions** — supervision strategies (Resume for coordinators, Stop
   for short-lived actors), `Tell` for hot paths / `Ask` only at system boundaries,
   message immutability, no blocking on non-blocking dispatchers, no `sender`/`this`
   captured in closures (`PipeTo` instead), correlation IDs on request/response.
3. **Concurrency & thread safety** — shared mutable state, actor state mutated only
   on the actor thread, race conditions, correct use of async/await.
4. **Error handling & resilience** — exception paths, store-and-forward integration,
   reconnect/retry logic, failover behaviour, transient vs permanent error
   classification, graceful degradation.
5. **Security** — authentication/authorization checks, input validation, the script
   trust model (forbidden APIs: `System.IO`, `Process`, `Threading`, `Reflection`,
   raw network), secret handling, SQL/LDAP injection, logging of sensitive data.
6. **Performance & resource management** — `IDisposable` disposal, stream/connection
   lifetimes, buffering and back-pressure, unnecessary allocations, N+1 queries.
7. **Design-document adherence** — does the code match `Component-<Name>.md` and the
   relevant CLAUDE.md decisions? Flag both code that drifts from the design and design
   docs that are now stale.
8. **Code organization & conventions** — persistence-ignorant POCO entities in
   Commons, repository interfaces in Commons / implementations in ConfigurationDatabase,
   namespace hierarchy, Options pattern (options classes owned by component projects),
   additive-only message contract evolution.
9. **Testing coverage** — are the module's behaviours covered by tests in `tests/`?
   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`](_template/findings.md).

- **Finding ID** — `<Module>-NNN`, numbered sequentially within the module and never
  reused (e.g. `TemplateEngine-001`). IDs are permanent even after resolution.
- **Severity:**
  - **Critical** — data loss, security breach, crash/deadlock, or cluster-wide 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 refresh 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** and
drop off the base README's pending list. `Open` and `In Progress` are **pending**.

## 5. Updating the base README

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

After any review or status change, regenerate it:

```
python3 code-reviews/regen-readme.py
```

`regen-readme.py --check` exits non-zero if `README.md` is stale, for use in CI.

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.