docs/modules/rust/PLAN.md

# `module-rust` — the plan

**Status:** approved in outline 2026-09-15, not started. Five decisions of record settled; one
question open (§3).

The [dry run](../rust-dryrun.md) designed this module on paper and deliberately did not build it.
This is the document that builds it. Where the two disagree, this one is later and wins — but the dry
run's four *findings* still stand, and one of them (identity) has moved from a footnote to the
critical path. §2 says why.

Nothing here is normative. [`MODULE_API.md`](../../website/MODULE_API.md) is the contract,
[`MODULE_SYSTEM.md`](../../website/MODULE_SYSTEM.md) the system, [`EVENTS.md`](../../website/EVENTS.md)
the event design of record, and the [Integration Kit][kit] is the teaching text this plan follows
chapter by chapter. This document is a *schedule and a set of decisions*, not a specification.

---

## 1. The shape, and what is already settled

Three new repositories, mirroring the three the platform already has for Ultima Online, plus the
optional fourth part that lives inside the module:

| Part | New repo | Mirrors | What it is |
|---|---|---|---|
| Website module | `RunicGateway/Module-rust` | `Module-uo` | Routes, schema fragment, prebuilt client chunk, nav |
| Sidecar | `RunicGateway/rust-link` | `link` | Owns the game connection and the durable copy |
| Oxide bridge plugin | `RunicGateway/rust-plugins` | `servuo-plugins` | C# inside the game, dials out, never blocks |
| *(event capability)* | — | — | Declarations inside `Module-rust` ([kit][kit] ch. 5) |

None exist yet. The module is built from [`integration-kit/template/`][kit], which CI holds against a
pinned core — currently `MODULE_API_VERSION` **1.10.0**.

Settled before this document and unchanged by it (dry run, org lead, 2026-08-19):

- **One server, one sidecar**, on that server's own host. A community with six servers runs six
  pairs; the module holds six clients and core never learns there is more than one.
- **The plugin dials out.** Rust's server is a binary, so the way in is Oxide's published hook API
  rather than source — and the shard-dials-out invariant survives that change of footing unchanged.
- **No RCON.** It was the original design and it was overruled.
- **`wipe_id` on every table that holds gameplay data.** It is the whole shape of the game in one
  column, and it is the first thing a UO-shaped mental model gets wrong.

## 2. Decisions of record

### R1 — identity is an in-game link code for v1

**Decided 2026-09-15 (org lead).** A player proves account ownership by typing a command in-game; the
plugin issues a one-time code; the website confirms it through the sidecar. Exactly the shape
`module-uo` uses.

This is the dry run's finding 1 answered for now rather than closed. There is still **no
`registerAuthProvider`** in the contract at 1.10.0 — verified against `MODULE_API.md` §2.4 on
2026-09-15 — so "Sign in with Steam", which every Rust community expects, is not reachable from a
module today. The link code is one screen worse and needs no core change, so it is what v1 ships.

**What changed since the dry run is the stakes, not the options.** The dry run rated this survivable
because the module only *read*: a site that renders a leaderboard does not need to know which account
owns a Steam ID. R2 makes the site the author of who may do what in the game, and R3 makes it the
thing that hands out loot. Both are grants against a Steam ID. **A weak identity link is now a
privilege-escalation path, not a missing convenience** — so the code must be single-use,
short-lived, rate-limited, and issued in-game to the player who will own it.

Adding `registerAuthProvider` properly stays the first candidate for a future `MODULE_API` bump. It
participates in session creation, which is the one part of core a module must never be able to
weaken, and it must inherit core's existing policy: **SSO is link-only, identities are never
auto-provisioned.** Specified deliberately, not bolted on. It is out of scope here.

### R2 — site-authored permissions are mirrored into Oxide's own permission store

**Decided 2026-09-15 (org lead).** The website is the author of record for groups and grants. The
bridge plugin applies them through Oxide's own API (`permission.GrantUserPermission` /
`RevokeUserPermission`), so **Oxide is an enforcement cache and the site is the thing that
remembers.**

The alternative — the plugin keeping a private table only our own features consult — was rejected
because it cannot reach any third-party plugin, and reaching them is the point: a grant authored on
the site has to gate Kits.

Three properties fall out, and they are the reason this shape is worth its cost:

- **Every third-party plugin honours site-authored grants with no adapter**, because they all already
  call `permission.UserHasPermission`.
- **A wipe stops being a data-loss event for permissions.** The game forgets; the site does not, and
  re-pushes the whole set on the next connect.
- **Hand edits are reported, not overwritten.** Somebody typing `oxide.grant` at the console is
  drift, and drift is surfaced to an operator — the same posture a lease's `restore()` takes when it
  finds a value a human has moved ([kit][kit] ch. 5).

**This is a direction the Integration Kit has no chapter for, and that is a finding.** Chapters 3 and
4 are the read path — data leaving the game. Chapter 5 is one-shot commands with a ledger and a
teardown. This is neither: it is *continuously reconciled state where the website is authoritative*,
and its nearest relative in the contract is the Team provider **inverted** — instead of core asking
the module what the game knows, the module tells the game what the site knows. The mechanism it
borrows is chapter 4's: **every board's current state has exactly one producer, and it runs on
connect**, pointed the other way. Whether this deserves a sixth chapter is a question for phase 10,
after it has been built once.

### R3 — the Kits reward action registers always and refuses with a reason

**Decided 2026-09-15 (org lead).** Kits is required for event rewards, but "required" means the
action always exists and fails honestly where it cannot work — `{ ok: false, retry: false, error:
'Kits plugin not installed' }` — rather than vanishing from the authoring form or refusing to boot
the module.

Two details from [kit][kit] ch. 5 that this depends on and are easy to get wrong:

- **The reason must be in `error`.** Core reads exactly `ok`, `retry` and `error` off a failure
  envelope; a message under any other name is dropped and the operator sees a bare
  `"<action id> refused"`.
- **`retry: false` has to be reachable.** Core's dispatcher enforces `budgetMs` and classifies a
  budget timeout as retry *unconditionally* — so if the sidecar client's timeout is longer than
  `budgetMs`, our own `retry: false` is unreachable code. Derive one constant from the other and
  assert the inequality in a test. The first module this project shipped had exactly that pairing.

### R4 — Rust reaches an operator through the existing installer, behind `--game`

**Decided 2026-09-15 (org lead).** Not a second binary and not a shared-core refactor: the shipped
[`installer`](../../installer/PLAN.md) grows a game dimension, `--game servuo|rust`, and keeps one
release stream, one `doctor`, one `update`, one `uninstall`.

The shape of the work is set by where the coupling already is. **The reusable half is already
game-agnostic** — `src/service.rs` and `src/main.rs` mention ServUO zero times, and `net.rs`,
`diff.rs`, `paths.rs` and `ui.rs` barely more. **The UO-specific half is concentrated in four files**
— `install.rs`, `doctor.rs`, `overlay.rs`, `tier.rs` — plus the bundle manifest, where
`OverlayComponent` and `ServUoCompat` name the game in the schema itself.

So the change is: make the bundle's game payload a **variant** rather than an overlay, and
`ServUoCompat` a per-game compat block. That is a schema change on the published **`bundles`**
branch, and it is the part to design before touching code.

**The Rust payload is much simpler than the UO one**, which is what makes this affordable: no source
tree to overlay, no `patches/`, no opt-in patch tier — a Rust install is a `.cs` file dropped into
`oxide/plugins/`, plus the sidecar and its service, which the installer already knows how to do. What
it gains instead is a **prerequisite check**: is Oxide installed, and is its build current enough.
That is `doctor`'s shape, not a new concept.

The protocol pairing check generalises unchanged. `servuo-plugins/overlay.toml` declares the protocol
the overlay speaks and the installer refuses to pair a disagreeing sidecar; `rust-plugins` needs the
same declaration under whatever name the variant gives it, and the refusal is the same refusal.

### R5 — Teams come from Rust's first-party clans; the uMod Clans plugin is the richer tier

**Decided 2026-09-15 (org lead).** Basic functionality is built on **Rust's own clan system**; the
third-party **uMod Clans plugin** is an optional layer for a much richer experience, and lands in
phase 9 rather than phase 6.

The distinction matters more than the names suggest, so it is worth stating precisely:

- **Rust's first-party clans** are seven hooks in [`HOOKS.md`](HOOKS.md) — `OnClanCreated`,
  `OnClanDisbanded`, `OnClanMemberAdded`, `OnClanMemberKicked`, `OnClanMemberLeft`, plus colour and
  logo — each handing you a `LocalClan`. **All seven are "no return behavior"**, which is exactly
  what a read-only bridge wants: there is nothing to abstain from, so [kit][kit] ch. 4's
  return-`null`-from-every-veto rule has no work to do here. They need no plugin, and the rig is
  already running them (`D:\rust\server\server1\clans.287.db`).
- **Rust's first-party *Teams* are a different system** — twelve hooks, mostly vetoable — and are the
  transient in-game squad, not the persistent organisation. They are **not** what core's Team
  provider should be fed. Clans is the right choice and this is why.
- **The uMod Clans plugin's API is not in our mirror.** [`HOOKS.md`](HOOKS.md) is the *game's* 477
  hooks; a plugin's own API is its own documentation. It is reached through `[PluginReference]` and
  is null when absent, making it an R3-shaped dependency that must refuse with a reason. It is also
  not currently staged locally and would need pulling and mirroring.

**The one gap to design around:** the seven first-party hooks carry created, disbanded, added,
kicked and left — but **no promote or leader-changed event**. Core's provider requires
`getTeamLeaders`, so leadership is read off `LocalClan` at snapshot time rather than tracked from
transitions. That makes phase 6 *partly* snapshot-driven where the dry run predicted it would be
fully event-driven — a small correction to that document, recorded here rather than silently.

## 3. Open question

**Which other uMod plugins are in the required base set?** Kits is named. The rest of "a couple" is
not, and phase 0 cannot finish its install list without it. Everything beyond the base set is
phase 9's optional tier.

`D:\rust\oxide\plugins\` is currently **empty**, so whatever the set is, all of it is a fresh install.

## 4. The test rig

`D:\rust` on the org lead's workstation. It has been booted, it has a generated world
(procedural, seed 1234, size 4000, save v287) and Oxide **2.0.7585** matched to its build, and its
Oxide permission store already holds a `default` and an `admin` group with one admin user — which
means R2's mechanism can be exercised on day one.

Two traps recorded here because both cost time before they were understood:

- **`D:\rust\start.bat` updated the wrong directory — fixed 2026-09-15.** It ran
  `steamcmd +force_install_dir c:\rustserver\ +app_update 258550` and then launched
  `D:\rust\RustDedicated.exe`. The server that boots had never been updated by its own script, which
  is why a second, never-booted install exists at `C:\rustserver` and why `D:\rust` is a wipe behind.
  Now reads `+force_install_dir d:\rust\`; the original is kept at `D:\rust\start.bat.bak`.
  `D:\rust\steamapps\appmanifest_258550.acf` was already present at the same buildid, so the first
  corrected run is a delta to the current wipe rather than a 5.9 GB re-download.
- **`C:\oxide_files` is a 2025-04-23 Oxide and must not be copied anywhere.** Oxide ships a patched
  `Assembly-CSharp.dll`; that bundle's is 6,842,880 bytes against the live 9,780,224, so copying it
  over a real install is a hard downgrade. `D:\rust` is already correct and needs nothing from it.

**Rust force-wipes on the first Thursday of the month and Oxide is rebuilt to match**, so "is the
rig current" is a recurring question, not a one-time setup step. Every phase that touches the plugin
re-checks it.

## 5. The phases

Phases 0–3 produce a working read-only Rust site. 4–5 are the permissions product. 6 is Teams. 7–8
are events. 9 is the optional tier. 10 is how any of it reaches somebody who is not us. Each phase
ends with its findings written down, as every workstream here does.

| # | Phase | Repos | Done when |
|---|---|---|---|
| 0 | **The rig.** Update to the current wipe (the script is fixed), confirm the Oxide build still matches, install the base set, prove a grant made at the console is visible to a plugin | docs | A current server boots with the base mods loaded and `oxide.grant` demonstrably gates something |
| 1 | **Protocol 1 and three skeletons.** Bounded drop-oldest queue, one writer thread, reconnect with a tagged epoch, dial-out; sidecar listener + SQLite + always-on token auth + version header; module from `template/` | all 3 + docs | One hello line travels game → sidecar → module, and killing the sidecar does not stall the game |
| 2 | **The read path.** First hook wave from [`HOOKS.md`](HOOKS.md); events and snapshots kept distinct at the wire; `wipe_id` everywhere; every board re-emitted on connect | all 3 + docs | A restarted sidecar is fully populated within one connection, with no negotiation |
| 3 | **The first pages.** Server list, per-server status, killfeed, leaderboard; `capabilities`; nav | Module-rust | The site renders the last thing the game said while the game is off |
| 4 | **Identity** (R1) | 3 + docs | A player links an account in-game and the site names their Steam ID |
| 5 | **Site-owned permissions** (R2). Groups and grants authored on the site; full set pushed on connect, deltas after; drift reported | all 3 + docs | A grant made on the website gates a third-party plugin in-game, and survives a wipe |
| 6 | **Teams provider** (R5). Rust's first-party clans; membership event-driven, leadership read off `LocalClan` at snapshot | Module-rust + 2 | Core's reconciler is answered from live transitions, `complete` claimed only per reachable server |
| 7 | **Events: one budget, one lease.** [kit][kit] ch. 5's own ordering — the lease before the action | Module-rust + 2 | The leased value is observed changing in the running game and restored, per key |
| 8 | **Events: the Kits reward action** (R3) | all 3 | A retried step grants loot once, and the ledger and the world agree |
| 9 | **Optional mod integrations**, the uMod **Clans** plugin first (R5). One adapter per plugin, each detecting via `[PluginReference]` and degrading to absent | rust-plugins + docs | A server missing every optional mod still runs the module, Teams included |
| 10 | **The installer** (R4). `--game servuo|rust`, the bundle payload as a variant, an Oxide prerequisite check in `doctor`, the protocol pairing refusal carried over | installer + docs | An operator sets a Rust server up with the released binary and nothing hand-copied |
| 11 | **Docs, kit feedback, cutover** | docs + Integration-kit | `docs/` describes what shipped; R2's missing chapter answered either way |

### Why the lease comes before the reward action

The stated priority is Kits rewards, and this plan still schedules a lease first. [kit][kit] ch. 5 is
explicit about it and the reasoning survives restating: a lease is *a value that already existed,
changed for a while, and put back*, so reading it first gives you the baseline for nothing. An action
makes something that did not exist. The lease proves the whole command path — correlation, the
idempotency key, `budgetMs` against the client timeout, the deadline the game enforces on its own —
before anything hands out loot. It is a cheaper place to find all four of chapter 5's invisible
failures.

Reversible on request.

### What phase 8 must declare honestly

**A kit grant cannot be `reversible: 'ledger'`.** That value is a promise that core may come back and
have the thing undone, on every terminal path including an abort — and there is no honest way to
un-grant loot a player has already spent. The correct declaration is `reversible: 'none'`, and saying
so is the point: a capability that claims a reversal it cannot perform is the "capability that lies"
chapter 5 names, and neither core nor review can catch it.

`cost()` must count the kits actually granted, derived from the params, every time. Core prices
`cost` before dispatch and never reconciles it against what came back — it cannot, it does not know
what a kit is — so an action that reports one while granting twelve turns an operator's cap of 30
into a cap of 360 with nothing anywhere going red.

And the monthly wipe is the case `revert`'s tolerance rule was written for: every ledgered resource
is invalidated at once, and **"gone, and that is fine" is a success**, not a failure.

## 6. Risks worth naming now

- **Hooks bind by name and arity, by reflection, with no compile-time check.** A misspelled hook is
  never called, silently, with no warning at load — the single most common way a Rust plugin does
  nothing. The plugin must log which of its expected hooks have fired at least once, so a hook
  Facepunch renamed on a wipe is visible rather than mysterious. See [`README.md`](README.md) §2.
- **A convar that applies cleanly and does nothing.** Most game config is read once at boot and
  cached; applying it later succeeds, reads back correctly, and changes nothing. Every lease key gets
  verified live — apply, observe in the running game, restore — before it is advertised. The UO
  module surveyed 156 config reads and found roughly eight that were live.
- **The wipe cadence is the schedule.** A monthly force wipe moves the hook list, rebuilds Oxide, and
  invalidates every ledgered resource. Phases that end near one should expect to re-verify rather
  than assume.
- **`start.bat`'s RCON password is `letmein` in plaintext with `rcon.web 1`.** Acceptable on a
  loopback dev rig, and it must never be the shape anything published copies.

[kit]: https://gitea.whitlocktech.com/RunicGateway/Integration-kit