Merge pull request 'feat(sidecar): protocol 8 — the asset plane (Asset Bridge cutover, 1 of 5)' (#44) from edge into main

Reviewed-on: #44
Reviewed-by: Colby Whitlock <whitlocktech@gmail.com>

.gitea/workflows/pr-checks.yml

@@ -17,10 +17,12 @@
 #   so let this workflow run on one PR first. The `PR Checks / *` glob matches
 #   without needing the dropdown.
 #
-# Scope note: this gates PRs into `main` only. Feature work that lands on an
-# integration branch first (e.g. `edge`) is still caught on the branch's PR into
-# `main`. To gate that earlier hop too, add the branch to the `branches:` list
-# below — nothing else needs to change.
+# Scope note: `edge` is gated as well as `main`. Multi-phase work lands there
+# first, so gating only the `main` hop would run these checks for the first time
+# at the cutover — the one moment a red build is most expensive to discover. This
+# is the same call `RunicGateway/installer` made for the same reason, and it was
+# taken here after a nine-PR Android workstream landed on an ungated `edge` with
+# no CI at all. Adding a branch to the `branches:` list is the whole change.
 #
 # Runner: the same self-hosted `ubuntu-latest` runner release.yml uses. Rust is
 # not assumed to be preinstalled, so the toolchain step bootstraps it the same
@@ -31,7 +33,7 @@ name: PR Checks
 
 on:
   pull_request:
-    branches: [main]
+    branches: [main, edge]
 
 # A newer push to the same PR cancels the in-flight run.
 concurrency:

.gitea/workflows/release.yml

@@ -28,6 +28,11 @@
 #                     write:package; THIS workflow additionally needs
 #                     `write:repository` so it can push the bump commit + tag
 #                     and create the release. Grant that scope to the token.
+#                     The final step also dispatches RunicGateway/installer's
+#                     bundle workflow, so the token ideally has write there too
+#                     — but that is a nicety, not a requirement: without it the
+#                     step warns and the installer's nightly cron picks the
+#                     release up instead.
 #   Also: `main` must accept a direct push from that user (disable branch
 #   protection for it, or add it as an exception) — the bump commit lands on main.
 #
@@ -51,6 +56,13 @@ env:
   BIN: uo-link-sidecar
   LINUX_TARGET: x86_64-unknown-linux-gnu
   WINDOWS_TARGET: x86_64-pc-windows-gnu
+  # Ampere/Graviton instances and Pi-class boxes are a realistic ServUO home,
+  # and the shard dials the sidecar out on loopback — so wherever the shard
+  # runs, this binary has to run too (installer PLAN.md §5.2).
+  ARM64_TARGET: aarch64-unknown-linux-gnu
+  # Notified after a release so the installer's compat matrix picks up this
+  # version immediately rather than at its next nightly run (PLAN.md §7.2).
+  INSTALLER_REPO: RunicGateway/installer
 
 jobs:
   release:
@@ -68,6 +80,8 @@ jobs:
       # ── RELEASE ENGINE: decide the next version + changelog ──────────────
       - name: Plan the release (version + changelog)
         id: plan
+        env:
+          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
         run: |
           set -euo pipefail
           mkdir -p dist
@@ -105,21 +119,92 @@ jobs:
             VERSION="$(bump "${LAST_TAG#v}" "$BUMP")"
           fi
 
+          # An existing tag is NOT automatically "nothing to do". A tag with no
+          # release behind it means a previous run tagged and then died before
+          # publishing — which is exactly what happened on servuo-plugins' first
+          # release, where absent REGISTRY_* secrets took the release API call to
+          # 401 after the tag had already been pushed. Standing down on the tag
+          # alone makes that state permanent: every later run sees the tag, sets
+          # RELEASE=false, and the release never appears. Note this deliberately
+          # OVERRIDES the RELEASE=false decided just above — with the tag in
+          # place there are no releasable commits after it, so the normal path
+          # would stand down, which is exactly why it could never self-heal.
+          REUSE_TAG=false
           if git rev-parse -q --verify "refs/tags/v${VERSION}" >/dev/null; then
-            echo "Tag v${VERSION} already exists — nothing to release."
+            CI_TOKEN="$(printf '%s' "${REGISTRY_TOKEN:-}" | tr -d '\r\n')"
+            REL_HTTP="$(curl -s -o /dev/null -w '%{http_code}' -H "Authorization: token ${CI_TOKEN}" "https://${GITEA_HOST}/api/v1/repos/${REPO}/releases/tags/v${VERSION}" || echo 000)"
+            if [ "$REL_HTTP" = "200" ]; then
+              echo "Tag v${VERSION} already has a release — nothing to do."
               RELEASE=false
+            elif [ "$REL_HTTP" = "404" ]; then
+              echo "::warning::Tag v${VERSION} exists but has no release — a previous run failed after tagging. Reusing the tag and publishing the release it is missing."
+              REUSE_TAG=true
+              RELEASE=true
+            else
+              # Anything else (000 from a network failure, 401/403 from a bad
+              # token) is not evidence of absence. Guessing "no release" would
+              # re-publish over a good one, so refuse instead.
+              echo "::error::Could not determine whether a release exists for v${VERSION} (HTTP ${REL_HTTP}). Refusing to guess."
+              exit 1
             fi
+          fi
+
+          # ── Orphan sweep ────────────────────────────────────────────────
+          #
+          # The check above is VERSION-SCOPED: it only ever asks about the one
+          # version this run computed. That is enough to recover an orphan on
+          # the very next run, and useless afterwards — once any releasable
+          # commit lands, the next run computes a NEW version, never looks at
+          # the old tag again, and the orphan becomes permanent and silent.
+          #
+          # servuo-plugins v0.1.0 is the proof, and the proof is pointed: the
+          # commit that ADDED the recovery above was itself typed
+          # `fix(release): ... recover the orphaned v0.1.0 tag`, so it bumped to
+          # v0.1.1 — and the run that introduced the recovery stepped straight
+          # past the tag it was written to rescue. That tag is still orphaned.
+          #
+          # So every v* tag is checked, and anything missing a release is
+          # WARNED about. Deliberately not recovered: publishing an old version
+          # would mean building today's tree and shipping it under a tag whose
+          # tree it is not, which is worse than the inconsistency it fixes.
+          # A human decides whether to recover or drop it.
+          #
+          # Never fails the run. A sweep that can break a good release is a
+          # sweep someone will delete.
+          ORPHANS=""
+          for T in $(git tag -l 'v*' --sort=-v:refname); do
+            T_HTTP="$(curl -s -o /dev/null -w '%{http_code}' \
+              -H "Authorization: token $(printf '%s' "${REGISTRY_TOKEN:-}" | tr -d '\r\n')" \
+              "https://${GITEA_HOST}/api/v1/repos/${REPO}/releases/tags/${T}" || echo 000)"
+            [ "$T_HTTP" = "404" ] && ORPHANS="${ORPHANS} ${T}"
+          done
+          if [ -n "${ORPHANS}" ]; then
+            echo "::warning::Tags with no release:${ORPHANS} — a run failed after tagging. Publish or delete them; this job will not do either."
+          fi
+
+          # Changelog range. A recovery run has nothing after the tag, so
+          # summarize what the tag itself contains rather than emitting an empty
+          # list: the range that produced it, i.e. previous-tag..this-tag.
+          if [ "$REUSE_TAG" = true ]; then
+            PREV_TAG="$(git describe --tags --match 'v*' --abbrev=0 "v${VERSION}^" 2>/dev/null || true)"
+            if [ -n "$PREV_TAG" ]; then CL_RANGE="${PREV_TAG}..v${VERSION}"; else CL_RANGE="v${VERSION}"; fi
+            SINCE="$PREV_TAG"
+          else
+            CL_RANGE="$RANGE"
+            SINCE="$LAST_TAG"
+          fi
+          CL_SUBJECTS="$(git log --no-merges --format='%s' $CL_RANGE || true)"
 
           {
             echo "## ${BIN} v${VERSION}"
             echo
-            FEATS="$(echo "$SUBJECTS" | grep -E '^feat'        || true)"
-            FIXES="$(echo "$SUBJECTS" | grep -E '^(fix|perf)'  || true)"
+            FEATS="$(echo "$CL_SUBJECTS" | grep -E '^feat'        || true)"
+            FIXES="$(echo "$CL_SUBJECTS" | grep -E '^(fix|perf)'  || true)"
             [ -n "$FEATS" ] && { echo "### Features";  echo "$FEATS" | sed 's/^/- /'; echo; }
             [ -n "$FIXES" ] && { echo "### Fixes";     echo "$FIXES" | sed 's/^/- /'; echo; }
             echo "### All changes"
-            if [ -n "$LAST_TAG" ]; then echo "Since ${LAST_TAG}:"; fi
-            echo "$SUBJECTS" | sed 's/^/- /'
+            if [ -n "$SINCE" ]; then echo "Since ${SINCE}:"; fi
+            echo "$CL_SUBJECTS" | sed 's/^/- /'
           } > dist/CHANGELOG.md
 
           echo "version=${VERSION}"   >> "$GITHUB_OUTPUT"
@@ -129,14 +214,26 @@ jobs:
           echo "==> release=${RELEASE} version=${VERSION} bump=${BUMP} last_tag=${LAST_TAG:-<none>}"
 
       # ── RUST ADAPTER: toolchain + cross-compile deps ─────────────────────
-      - name: Install Rust toolchain, Windows target, and MinGW linker
+      - name: Install Rust toolchain, cross targets, and their linkers
         if: ${{ steps.plan.outputs.release == 'true' }}
         run: |
           set -euo pipefail
           SUDO=""; [ "$(id -u)" -ne 0 ] && SUDO="sudo"
           $SUDO apt-get update
+          # The arm64 cross toolchain is not optional for this crate: sqlx's
+          # sqlite feature pulls libsqlite3-sys, which compiles bundled SQLite
+          # from C, so a Rust-only cross build fails at the first .c file.
+          #
+          # libc6-dev-arm64-cross is named explicitly because gcc-aarch64-linux-gnu
+          # only *recommends* it, and this install is --no-install-recommends: the
+          # compiler arrives without arm64 libc headers and SQLite's build dies on
+          # `bits/libc-header-start.h: No such file or directory`. Verified by
+          # reproducing both the failure and the fix in a rust:1-slim-bookworm
+          # container.
           $SUDO apt-get install -y --no-install-recommends \
-            build-essential gcc-mingw-w64-x86-64 curl ca-certificates git jq
+            build-essential gcc-mingw-w64-x86-64 \
+            gcc-aarch64-linux-gnu libc6-dev-arm64-cross \
+            curl ca-certificates git jq
 
           if ! command -v cargo >/dev/null 2>&1; then
             curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
@@ -146,6 +243,7 @@ jobs:
           export PATH="${HOME}/.cargo/bin:${PATH}"
           rustup component add rustfmt
           rustup target add "${WINDOWS_TARGET}"
+          rustup target add "${ARM64_TARGET}"
 
       - name: Set the crate version to match the release
         if: ${{ steps.plan.outputs.release == 'true' }}
@@ -187,45 +285,80 @@ jobs:
           AR_x86_64_pc_windows_gnu: x86_64-w64-mingw32-ar
         run: cargo build --release --locked --target "${WINDOWS_TARGET}"
 
+      # Same shape as the Windows step: a linker for Rust's output and a CC/AR
+      # pair for the cc-crate build of bundled SQLite.
+      - name: cargo build --release (Linux arm64, cross via aarch64-linux-gnu)
+        if: ${{ steps.plan.outputs.release == 'true' }}
+        working-directory: sidecar
+        env:
+          CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: aarch64-linux-gnu-gcc
+          CC_aarch64_unknown_linux_gnu: aarch64-linux-gnu-gcc
+          AR_aarch64_unknown_linux_gnu: aarch64-linux-gnu-ar
+        run: cargo build --release --locked --target "${ARM64_TARGET}"
+
       # ── RUST ADAPTER: package artifacts (+ checksums) ────────────────────
       - name: Package artifacts and SHA256SUMS
         if: ${{ steps.plan.outputs.release == 'true' }}
         run: |
           set -euo pipefail
           cp "${WORKDIR}/target/${LINUX_TARGET}/release/${BIN}"        "dist/${BIN}-linux-x86_64"
+          cp "${WORKDIR}/target/${ARM64_TARGET}/release/${BIN}"        "dist/${BIN}-linux-aarch64"
           cp "${WORKDIR}/target/${WINDOWS_TARGET}/release/${BIN}.exe"  "dist/${BIN}-windows-x86_64.exe"
-          ( cd dist && sha256sum "${BIN}-linux-x86_64" "${BIN}-windows-x86_64.exe" > SHA256SUMS )
+          # Every artifact must appear here: the installer verifies its download
+          # against these sums, and `sha256sum -c` passes silently over a file
+          # this list does not mention.
+          ( cd dist && sha256sum "${BIN}-linux-x86_64" "${BIN}-linux-aarch64" \
+              "${BIN}-windows-x86_64.exe" > SHA256SUMS )
           ls -l dist && echo "----" && cat dist/SHA256SUMS
 
       # ── RELEASE ENGINE: commit the bump, tag, push ───────────────────────
-      - name: Commit version bump and push tag
+      # Tag only — `main` is never pushed to.
+      #
+      # This step used to commit the version bump back to main first. Two things
+      # were wrong with that. It has never once executed: an EMPTY template
+      # expression written literally in a comment (the `$`+`{{ }}` token, which
+      # is why it is spelled out here) made the runner fail to build the script
+      # and skip the whole step silently, which is why sidecar/Cargo.toml still
+      # says 0.1.0 after six releases (the tags exist because the release API
+      # creates one when it publishes). And had it executed, it would have been
+      # declined — main is protected, and a release must not depend on a write
+      # to a protected branch.
+      #
+      # So the tag is the version, as it already is in servuo-plugins. The
+      # workflow still writes the real version into Cargo.toml before building,
+      # so a released binary self-reports correctly; what it no longer does is
+      # commit that edit back. The next version is computed from the newest tag,
+      # never from Cargo.toml, so nothing downstream depends on the file.
+      - name: Push the release tag
         if: ${{ steps.plan.outputs.release == 'true' }}
         env:
           REGISTRY_USER: ${{ secrets.REGISTRY_USER }}
           REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
         run: |
           set -euo pipefail
-          VERSION="${{ steps.plan.outputs.version }}"
           TAG="${{ steps.plan.outputs.tag }}"
           # Secrets can arrive with a trailing newline (depending on how they were
           # pasted); a stray CR/LF corrupts the remote URL ("credential url cannot
-          # be parsed"). Strip line breaks before building the URL. Passing them via
-          # env (not inline ${{ }}) also keeps a newline from breaking this script.
+          # be parsed"). Strip line breaks before building the URL. They are passed
+          # via env rather than interpolated into this script, so a newline cannot
+          # break it — do NOT write a template token literally in a comment here,
+          # or the runner will skip this step without failing the job.
           CI_USER="$(printf '%s' "${REGISTRY_USER}" | tr -d '\r\n')"
           CI_TOKEN="$(printf '%s' "${REGISTRY_TOKEN}" | tr -d '\r\n')"
           git config user.name  "uo-link-ci"
           git config user.email "ci@whitlocktech.com"
           git remote set-url origin \
             "https://${CI_USER}:${CI_TOKEN}@${GITEA_HOST}/${REPO}.git"
-
-          git add "${WORKDIR}/Cargo.toml" "${WORKDIR}/Cargo.lock"
-          if ! git diff --cached --quiet; then
-            git commit -m "chore(release): bump version to ${TAG} [skip ci]"
-            git push origin "HEAD:main"
+          # The tag may already exist when finishing a run that died after tagging
+          # (see the plan step). `git tag` on an existing name fails under
+          # `set -e`; pushing an identical existing tag is a harmless no-op. A
+          # push that fails here means the remote tag points somewhere else,
+          # which SHOULD stop the run.
+          if git rev-parse -q --verify "refs/tags/${TAG}" >/dev/null; then
+            echo "Tag ${TAG} already exists — reusing it."
           else
-            echo "Version unchanged (first release) — no bump commit needed."
-          fi
             git tag "${TAG}"
+          fi
           git push origin "${TAG}"
 
       # ── RELEASE ENGINE: create the Gitea release + upload assets ─────────
@@ -242,17 +375,116 @@ jobs:
           # corrupt the Authorization header.
           CI_TOKEN="$(printf '%s' "${REGISTRY_TOKEN}" | tr -d '\r\n')"
 
-          REL_ID="$(curl -sSf -X POST "${API}/releases" \
+          PAYLOAD="$(jq -n --arg tag "$TAG" --arg body "$BODY" \
+                       '{tag_name:$tag, name:$tag, body:$body, draft:false, prerelease:false}')"
+
+          # This POST is the step that orphaned tag v0.1.1 (run 75): it landed one
+          # second after the tag push and Gitea answered 500, having not finished
+          # processing the pushed tag. Re-running the workflow published the same
+          # four assets untouched, so the failure was a race, not a bad request.
+          #
+          # Two things went wrong there, and both are fixed here.
+          #
+          # 1. `curl -sSf` prints NO response body on an error status, so all the
+          #    log carried was "curl: (22) ... error: 500" and the cause had to be
+          #    inferred from timestamps. Capture the body and print it.
+          # 2. Nothing retried, so a transient 5xx became a permanent orphan tag.
+          #    The plan step CAN recover one, but only on a run that reaches it --
+          #    and a later push with no releasable commits stands down before it
+          #    gets there, so in practice the tag sits until a human notices.
+          #
+          # 4xx is deliberately NOT retried: a bad token or a malformed body does
+          # not improve by being sent again, and retrying only turns a clear
+          # failure into a slow one.
+          REL_ID=""
+          for attempt in 1 2 3 4 5; do
+            HTTP="$(curl -s -o /tmp/rel.json -w '%{http_code}' -X POST "${API}/releases" \
               -H "Authorization: token ${CI_TOKEN}" \
               -H "Content-Type: application/json" \
-            -d "$(jq -n --arg tag "$TAG" --arg body "$BODY" \
-                   '{tag_name:$tag, name:$tag, body:$body, draft:false, prerelease:false}')" \
-            | jq -r '.id')"
+              -d "${PAYLOAD}" || echo 000)"
+
+            if [ "$HTTP" = "201" ] || [ "$HTTP" = "200" ]; then
+              REL_ID="$(jq -r '.id' /tmp/rel.json)"
+              break
+            fi
+
+            echo "::warning::POST /releases attempt ${attempt} returned HTTP ${HTTP}"
+            echo "--- response body ---"
+            cat /tmp/rel.json || true
+            echo
+            echo "---------------------"
+
+            case "$HTTP" in
+              4*) echo "::error::HTTP ${HTTP} is a client error - not retrying."; exit 1 ;;
+            esac
+
+            if [ "$attempt" = 5 ]; then
+              echo "::error::POST /releases still failing after 5 attempts. Tag ${TAG} is pushed but has no release."
+              echo "::error::Re-run this workflow - the plan step detects the orphan tag and republishes it."
+              exit 1
+            fi
+            sleep $(( attempt * 5 ))
+          done
+
+          if [ -z "$REL_ID" ] || [ "$REL_ID" = "null" ]; then
+            echo "::error::Release created but no id came back; refusing to upload assets blind."
+            exit 1
+          fi
           echo "Created release ${TAG} (id=${REL_ID})"
 
-          for f in "${BIN}-linux-x86_64" "${BIN}-windows-x86_64.exe" SHA256SUMS; do
-            curl -sSf -X POST "${API}/releases/${REL_ID}/assets?name=${f}" \
+          for f in "${BIN}-linux-x86_64" "${BIN}-linux-aarch64" "${BIN}-windows-x86_64.exe" SHA256SUMS; do
+            # Same treatment. An upload that fails quietly leaves a release whose
+            # SHA256SUMS does not cover every binary it advertises, which is worse
+            # than no release at all -- that file IS the trust anchor.
+            HTTP="$(curl -s -o /tmp/asset.json -w '%{http_code}' -X POST "${API}/releases/${REL_ID}/assets?name=${f}" \
               -H "Authorization: token ${CI_TOKEN}" \
-              -F "attachment=@dist/${f}" >/dev/null
+              -F "attachment=@dist/${f}" || echo 000)"
+            if [ "$HTTP" != "201" ] && [ "$HTTP" != "200" ]; then
+              echo "::error::uploading ${f} returned HTTP ${HTTP}"
+              cat /tmp/asset.json || true
+              exit 1
+            fi
             echo "  uploaded ${f}"
           done
+
+      # ── Recompose the installer's bundle manifest ────────────────────────
+      # The installer does not resolve "latest" at run time — it installs the
+      # exact combination named by a published bundle (docs/installer/PLAN.md
+      # §7.1). So a sidecar release that nobody recomposes around is a release
+      # no operator will ever be offered. This step tells the installer repo to
+      # rebuild that manifest now, instead of leaving the new version invisible
+      # until its nightly cron.
+      #
+      # DISPATCH, DON'T WAIT (PLAN.md §7.3). Gitea's workflow-dispatch endpoint
+      # returns no run handle, so there is nothing to poll: a waiting step would
+      # have to guess which run is its own and hold a runner idle to do it. The
+      # bundle job runs its own gates regardless of who started it.
+      #
+      # A failure here is a WARNING, never a failure of this job. The release is
+      # already published and correct by this point; failing the run would
+      # misreport that. The installer's nightly cron recomposes from whatever
+      # the latest releases actually are, so a dropped dispatch self-heals — it
+      # costs latency, not correctness.
+      #
+      # `repository_dispatch` is deliberately not used: support for it is
+      # uncertain on this Gitea version, while dispatching an existing
+      # workflow_dispatch workflow via the API works today.
+      - name: Ask the installer repo to recompose its bundle
+        if: ${{ steps.plan.outputs.release == 'true' }}
+        env:
+          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
+        run: |
+          set -euo pipefail
+          CI_TOKEN="$(printf '%s' "${REGISTRY_TOKEN}" | tr -d '\r\n')"
+          HTTP="$(curl -s -o /dev/null -w '%{http_code}' -X POST \
+            -H "Authorization: token ${CI_TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d '{"ref":"main"}' \
+            "https://${GITEA_HOST}/api/v1/repos/${INSTALLER_REPO}/actions/workflows/bundle.yml/dispatches" || echo 000)"
+          case "$HTTP" in
+            20*) echo "Dispatched ${INSTALLER_REPO} bundle.yml (HTTP ${HTTP}) — not waiting for it." ;;
+            403|404)
+              echo "::warning::Could not dispatch ${INSTALLER_REPO} bundle.yml (HTTP ${HTTP}). REGISTRY_TOKEN likely lacks write:repository on that repo. Release ${{ steps.plan.outputs.tag }} is published and fine; its bundle will be composed by the installer's nightly cron instead." ;;
+            *)
+              echo "::warning::Dispatching ${INSTALLER_REPO} bundle.yml returned HTTP ${HTTP}. Release ${{ steps.plan.outputs.tag }} is published and fine; the nightly cron will recompose the bundle." ;;
+          esac

README.md

@@ -12,11 +12,34 @@ ServUO plugin (C#, net48)  ──loopback TCP, newline-JSON──►  Rust sidec
 The shard never speaks WebSocket and exposes no port of its own — the sidecar is the only
 network-facing component, which is what keeps the game unreachable from the internet.
 
+## Running a shard? Don't build this
+
+The [**Runic Gateway installer**](https://gitea.whitlocktech.com/RunicGateway/installer) installs
+this sidecar for you — the released binary, its config, a hardened service account and the service
+registration — alongside the shard plugin, in one run, on Linux or Windows:
+
+```bash
+sudo ./runicgateway-installer-linux-x86_64 install
+```
+
+It ends by printing the base URL, WebSocket URL, protocol version and auth token to paste into
+**Admin → Shard** on your site. Guide:
+[installer/INSTALL.md](https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/installer/INSTALL.md).
+
+Installing it yourself is supported too — the release binaries on this repo's
+[releases page](https://gitea.whitlocktech.com/RunicGateway/link/releases) are the same ones the
+installer fetches, and
+[INSTALL.md Appendix A3–A4](https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/installer/INSTALL.md#a3-install-the-sidecar)
+covers placing the binary and registering the service by hand.
+
+Everything below this line is for **developing on the sidecar**.
+
 ## Related repos
 
 | Repo | What |
 |------|------|
 | **this** — `RunicGateway/link` | The Rust sidecar (`sidecar/`). |
+| [RunicGateway/installer](https://gitea.whitlocktech.com/RunicGateway/installer) | The **installer** — deploys this sidecar and the plugin onto a shard host. The supported way to set one up. |
 | [RunicGateway/servuo-plugins](https://gitea.whitlocktech.com/RunicGateway/servuo-plugins) | The **C# ServUO plugin** — the shard side of the bridge (`overlay/`, `patches/`, `deploy.ps1`, test scaffolding). |
 | [RunicGateway/docs](https://gitea.whitlocktech.com/RunicGateway/docs) | All project documentation — design docs, protocol spec, integration guide, research. |
 
@@ -28,9 +51,10 @@ network-facing component, which is what keeps the game unreachable from the inte
 | `.gitea/workflows/pr-checks.yml` | Gates every PR into `main` on `cargo fmt --check`, `cargo clippy -D warnings`, and `cargo test`. |
 | `.gitea/workflows/release.yml` | Builds + releases the sidecar binary (Linux + Windows) on every merge to `main`. |
 
-## Build & run
+## Build & run (development)
 
-The sidecar is a standard cargo crate:
+Building from source is for working *on* the sidecar; a deployment gets its binary from a release,
+via the installer or by hand. The sidecar is a standard cargo crate:
 
 ```bash
 cd sidecar
@@ -39,7 +63,7 @@ cp sidecar.toml.example sidecar.toml   # then edit
 cargo run --release
 ```
 
-Deploying it rather than developing on it: `--config <PATH>` names the config file (as does
+Deploying it by hand rather than developing on it: `--config <PATH>` names the config file (as does
 `$UOLINK_CONFIG`), and `--print-config` prints the resolved settings — **including the auth token
 the website needs** — as JSON, provisioning the config file on first run. That is the supported way
 to read the token back; it is not meant to be scraped from the log.
@@ -48,6 +72,29 @@ to read the token back; it is not meant to be scraped from the log.
 uo-link-sidecar --print-config --config /etc/runicgateway/sidecar.toml
 ```
 
+### Running as a service
+
+The same binary runs in the foreground and as a system service — there is no `--service` flag to
+remember, because the process can tell how it was started.
+
+- **Linux/systemd** supervises any foreground process, so the unit just runs the binary. `SIGTERM`
+  (what `systemctl stop` sends) and `SIGINT` both unwind it cleanly; logs go to the journal.
+- **Windows** cannot. The service control manager only supervises a process that connects back to
+  it within ~30 seconds via `StartServiceCtrlDispatcher`; a plain console program registered with
+  `sc.exe create` is killed with **error 1053** despite running perfectly. So on Windows the sidecar
+  speaks that handshake: started by the SCM it runs as a service, started from a shell the connect
+  fails with `ERROR_FAILED_SERVICE_CONTROLLER_CONNECT` and it falls through to an ordinary
+  foreground run. It reports `Running` only once the shard port is bound and the store is open, and
+  — having no console — logs to `uo-link-sidecar.<date>.log` beside its config, rolled daily.
+
+Only the starting and stopping is platform-specific: `src/app.rs` is the entire sidecar and is
+shared, while `src/windows.rs` and `src/unix.rs` do nothing but start it and tell it when to stop.
+The Windows crates are declared under `[target.'cfg(windows)'.dependencies]`, so Cargo neither
+resolves nor builds them for a Linux target.
+
+Registering the service is the installer's job; to do it by hand see
+[INSTALL.md Appendix A4](https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/installer/INSTALL.md).
+
 `.gitea/workflows/release.yml` cross-compiles Linux + Windows binaries and cuts a Gitea release on
 every merge to `main` (conventional-commit versioning). See [`sidecar/README.md`](sidecar/README.md)
 for configuration and the wire protocol.

sidecar/Cargo.lock

@@ -242,6 +242,15 @@ version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "217698eaf96b4a3f0bc4f3662aaa55bdf913cd54d7204591faa790070c6d0853"
 
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d85363c37faeca707aef026efa9f3b34d077bce547e48f770770625c6013679e"
+dependencies = [
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-queue"
 version = "0.3.13"
@@ -284,6 +293,12 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "deranged"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cd812cc2bc1d69d4764bd80df88b4317eaef9e773c75226407d9bc0876b211c"
+
 [[package]]
 name = "digest"
 version = "0.10.7"
@@ -921,6 +936,12 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "num-conv"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "521739c6d2bac4aa25192232afe6841231376b2b26d4d9fae5ecf8ca5772e441"
+
 [[package]]
 name = "num-integer"
 version = "0.1.46"
@@ -1048,6 +1069,12 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "powerfmt"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "439ee305def115ba05938db6eb1644ff94165c5ab5e9420d1c1bcedbba909391"
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.21"
@@ -1565,6 +1592,12 @@ version = "2.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
 
+[[package]]
+name = "symlink"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7973cce6668464ea31f176d85b13c7ab3bba2cb3b77a2ed26abd7801688010a"
+
 [[package]]
 name = "syn"
 version = "2.0.118"
@@ -1642,6 +1675,36 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "time"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb87b95ec50ddfa440816d227a17b2ccbdda963a316a727fda0fc4334f7d134"
+dependencies = [
+ "deranged",
+ "num-conv",
+ "powerfmt",
+ "serde_core",
+ "time-core",
+ "time-macros",
+]
+
+[[package]]
+name = "time-core"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e1c906769ad99c88eaa54e728060edef082f8e358ff32030cb7c7d315e81109"
+
+[[package]]
+name = "time-macros"
+version = "0.2.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e689342a48d2ea927c87ea50cabf8594854bf940e9310208848d680d668ed85"
+dependencies = [
+ "num-conv",
+ "time-core",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.3"
@@ -1798,6 +1861,19 @@ dependencies = [
  "tracing-core",
 ]
 
+[[package]]
+name = "tracing-appender"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "050686193eb999b4bb3bc2acfa891a13da00f79734704c4b8b4ef1a10b368a3c"
+dependencies = [
+ "crossbeam-channel",
+ "symlink",
+ "thiserror 2.0.18",
+ "time",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-attributes"
 version = "0.1.31"
@@ -1913,7 +1989,9 @@ dependencies = [
  "tokio",
  "toml",
  "tracing",
+ "tracing-appender",
  "tracing-subscriber",
+ "windows-service",
 ]
 
 [[package]]
@@ -2025,6 +2103,12 @@ dependencies = [
  "wasite",
 ]
 
+[[package]]
+name = "widestring"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72069c3113ab32ab29e5584db3c6ec55d416895e60715417b5b883a357c3e471"
+
 [[package]]
 name = "windows-core"
 version = "0.62.2"
@@ -2075,6 +2159,17 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "windows-service"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "857224b3b211c6f3616921f081ee54721ee3ad2ace2fac6a6337e032f7b4dcf2"
+dependencies = [
+ "bitflags",
+ "widestring",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "windows-strings"
 version = "0.5.1"

sidecar/Cargo.toml

@@ -17,5 +17,12 @@ toml = "0.8"
 getrandom = "0.2"
 chrono = { version = "0.4", default-features = false, features = ["std", "clock"] }
 
+# Speaking the Windows Service Control Manager's startup handshake, and logging somewhere other
+# than the stdout a service does not have. Declared per target so Cargo neither resolves nor builds
+# either crate for Linux — the Linux binary is byte-for-byte unaffected by Windows service support.
+[target.'cfg(windows)'.dependencies]
+windows-service = "0.8"
+tracing-appender = "0.2"
+
 [profile.release]
 opt-level = 2

sidecar/src/app.rs

@@ -0,0 +1,571 @@
+//! The sidecar itself: everything that happens between "we have a config path" and "we were told
+//! to stop". Identical on every platform.
+//!
+//! This module exists so that *how the process is started and stopped* — a bare `main` under
+//! systemd, or a `ServiceMain` under the Windows SCM — is the only thing that differs between
+//! hosts. The shard listener, the config, the store, the web server and the event loop are shared
+//! code with no `#[cfg]` in sight.
+//!
+//! [`run`] is parameterised on the two things a supervisor cares about:
+//!
+//! - `ready` is called once the sidecar is actually up (listener bound, store open). The Windows
+//!   service reports `Running` to the SCM there, so a config or bind failure surfaces as a *start*
+//!   failure rather than a service that reports Running and then dies.
+//! - `shutdown` is whatever "stop" means on this host: Ctrl-C and `SIGTERM` on Unix, the SCM's
+//!   `Stop` control on Windows.
+
+use std::collections::HashMap;
+use std::future::Future;
+use std::sync::atomic::AtomicI64;
+use std::sync::Arc;
+use std::time::Instant;
+
+use serde_json::Value;
+use tokio::sync::{broadcast, mpsc};
+use tracing::info;
+
+use crate::{config, rpc, shard, store, web};
+
+/// Runs the sidecar until `shutdown` resolves.
+///
+/// `config_path` is the `--config` argument, or `None` to resolve `$UOLINK_CONFIG` and the default
+/// as usual.
+pub async fn run<R, S>(config_path: Option<&str>, ready: R, shutdown: S) -> anyhow::Result<()>
+where
+    R: FnOnce(),
+    S: Future<Output = ()>,
+{
+    info!("uo-link sidecar starting");
+
+    let loaded = config::Config::load(config_path)?;
+    let cfg = loaded.cfg;
+    info!(
+        config = %loaded.path.display(),
+        shard = %cfg.shard.bind,
+        web = %cfg.web.bind,
+        db = %cfg.store.path,
+        auth = cfg.auth_required(),
+        "configuration loaded"
+    );
+
+    // Shard link: events in, commands out.
+    let (event_tx, mut event_rx) = mpsc::unbounded_channel::<shard::ShardEvent>();
+    let handle = shard::serve(&cfg.shard.bind, event_tx).await?;
+
+    // Live feed: every shard event fans out to all connected website WebSocket clients.
+    let (bcast_tx, _) = broadcast::channel::<String>(1024);
+
+    // Request/reply correlation for REST queries.
+    let rpc = rpc::Rpc::new();
+
+    // Durable store: event history, economy series, cached profiles, link map.
+    let store = store::Store::open(&cfg.store.path).await?;
+
+    // Health/observability state.
+    let started = Instant::now();
+    let last_event = Arc::new(AtomicI64::new(0));
+
+    // Website-facing HTTP server.
+    let web_state = web::AppState {
+        events: bcast_tx.clone(),
+        shard: handle.clone(),
+        rpc: rpc.clone(),
+        store: store.clone(),
+        token: Arc::new(cfg.web.auth_token.clone()),
+        started,
+        last_event: last_event.clone(),
+    };
+    let web_bind = cfg.web.bind.clone();
+    tokio::spawn(async move {
+        if let Err(e) = web::serve(&web_bind, web_state).await {
+            tracing::error!(error = %e, "web server exited");
+        }
+    });
+
+    // Event loop: a line that correlates to a pending REST call is a reply — route it to the
+    // waiting caller and stop. Everything else is a live event: log it, persist it, broadcast it.
+    let feed_tx = bcast_tx.clone();
+    let route_rpc = rpc.clone();
+    let event_store = store.clone();
+    let last_event_ts = last_event.clone();
+    let replay_handle = handle.clone(); // re-push external news to the shard on (re)connect
+    let mut total: u64 = 0;
+    // Partly-received guild rosters, keyed by guild id. Lives in the event-loop task, so it needs
+    // no lock and dies with the loop. See `accumulate_roster`.
+    let mut roster_parts: HashMap<i64, RosterParts> = HashMap::new();
+    tokio::spawn(async move {
+        while let Some(ev) = event_rx.recv().await {
+            // Any line from the shard — including pong heartbeats — is a sign of life.
+            last_event_ts.store(now_ms(), std::sync::atomic::Ordering::Relaxed);
+
+            if route_rpc.try_route(&ev.value).await {
+                continue; // consumed as a reply
+            }
+
+            total += 1;
+            match ev.kind.as_str() {
+                "server.hello" | "mob.login" | "mob.logout" | "player.death" | "vendor.sale"
+                | "house.decay" | "link.request" => {
+                    info!(kind = %ev.kind, n = total, "{}", ev.value);
+                }
+                _ => tracing::debug!(kind = %ev.kind, n = total, "{}", ev.value),
+            }
+
+            // Persist, then broadcast. `pong` and `ws.hello` are ephemeral chatter, not history.
+            if ev.kind != "pong" {
+                let t = ev
+                    .value
+                    .get("t")
+                    .and_then(|v| v.as_i64())
+                    .unwrap_or_else(now_ms);
+                let text = ev.value.to_string();
+                if let Err(e) = event_store.insert_event(t, &ev.kind, &text).await {
+                    tracing::warn!(error = %e, "failed to persist event");
+                }
+
+                // The champ board is a live projection: champ.update folds in the latest state (one
+                // row per spawn), champ.remove drops a spawn that despawned or was slain.
+                match ev.kind.as_str() {
+                    "champ.update" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store
+                                .upsert_champ(
+                                    serial,
+                                    ev.value.get("status").and_then(|s| s.as_str()),
+                                    ev.value.get("name").and_then(|n| n.as_str()),
+                                    &text,
+                                    t,
+                                )
+                                .await
+                            {
+                                tracing::warn!(error = %e, "failed to upsert champ board");
+                            }
+                        }
+                    }
+                    "champ.remove" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store.delete_champ(serial).await {
+                                tracing::warn!(error = %e, "failed to remove champ board row");
+                            }
+                        }
+                    }
+                    // Guild board (Protocol 2.0): guild.update folds in the latest roster (one row
+                    // per guild id); guild.remove drops a disbanded guild.
+                    "guild.update" => {
+                        if let Some(id) = ev.value.get("id").and_then(|v| v.as_i64()) {
+                            if let Err(e) = event_store
+                                .upsert_guild(
+                                    id,
+                                    ev.value.get("name").and_then(|n| n.as_str()),
+                                    &text,
+                                    t,
+                                )
+                                .await
+                            {
+                                tracing::warn!(error = %e, "failed to upsert guild board");
+                            }
+                        }
+                    }
+                    // Guild roster (Protocol 4): the member list that `guild.update`'s counts cannot
+                    // express. It writes a *different column* of the same row, so it never races
+                    // guild.update. `guild.leave` deliberately has no arm here — the sidecar
+                    // forwards it (persisted and broadcast below, like any event) and the board's
+                    // roster self-corrects on the next `guild.roster`, which the shard re-emits
+                    // whenever the member set changes. Keeping the delta out of the board is what
+                    // keeps the sidecar a forwarder rather than a thing that maintains state.
+                    //
+                    // A roster over the shard's per-line cap arrives as several frames, so it is
+                    // reassembled before it is stored — see `accumulate_roster` for why that happens
+                    // here rather than by appending to the column.
+                    "guild.roster" => {
+                        if let Some(id) = ev.value.get("id").and_then(|v| v.as_i64()) {
+                            let seq = ev.value.get("seq").and_then(|v| v.as_i64()).unwrap_or(0);
+                            let more = ev
+                                .value
+                                .get("more")
+                                .and_then(|v| v.as_bool())
+                                .unwrap_or(false);
+                            let members = ev
+                                .value
+                                .get("members")
+                                .and_then(|m| m.as_array())
+                                .cloned()
+                                .unwrap_or_default();
+
+                            if let Some(complete) =
+                                accumulate_roster(&mut roster_parts, id, seq, more, members)
+                            {
+                                let json = serde_json::Value::Array(complete).to_string();
+                                if let Err(e) = event_store.upsert_guild_roster(id, &json, t).await
+                                {
+                                    tracing::warn!(error = %e, "failed to upsert guild roster");
+                                }
+                            }
+                        }
+                    }
+                    "guild.remove" => {
+                        if let Some(id) = ev.value.get("id").and_then(|v| v.as_i64()) {
+                            if let Err(e) = event_store.delete_guild(id).await {
+                                tracing::warn!(error = %e, "failed to remove guild board row");
+                            }
+                        }
+                    }
+                    // Governor board (Protocol 2.0): city.update folds in each city's latest
+                    // governance state (one row per city).
+                    "city.update" => {
+                        if let Some(city) = ev.value.get("city").and_then(|c| c.as_str()) {
+                            if let Err(e) = event_store.upsert_governor(city, &text, t).await {
+                                tracing::warn!(error = %e, "failed to upsert governor board");
+                            }
+                        }
+                    }
+                    // House registry (Protocol 2.0): house.update folds in each house's latest state
+                    // (one row per serial); house.remove drops a demolished/traded house.
+                    "house.update" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store
+                                .upsert_house(
+                                    serial,
+                                    ev.value.get("name").and_then(|n| n.as_str()),
+                                    &text,
+                                    t,
+                                )
+                                .await
+                            {
+                                tracing::warn!(error = %e, "failed to upsert house registry");
+                            }
+                        }
+                    }
+                    "house.remove" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store.delete_house(serial).await {
+                                tracing::warn!(error = %e, "failed to remove house registry row");
+                            }
+                        }
+                    }
+                    // Points/loyalty boards (Protocol 3.0): one row per point system, keyed by
+                    // the shard's own PointsType name. The plugin only emits a system whose top N
+                    // actually moved, so this is a sparse stream of overwrites — and there is no
+                    // `points.remove` to handle, because the shard's set of systems is fixed at
+                    // startup and cannot shrink.
+                    "points.board" => {
+                        if let Some(system) = ev.value.get("system").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store
+                                .upsert_points_board(
+                                    system,
+                                    ev.value.get("nameString").and_then(|n| n.as_str()),
+                                    &text,
+                                    t,
+                                )
+                                .await
+                            {
+                                tracing::warn!(error = %e, "failed to upsert points board");
+                            }
+                        }
+                    }
+                    // Player-vendor market index (Protocol 3.0). Each frame is authoritative for
+                    // one vendor — the shard's round-robin sweep only emits a shop whose contents,
+                    // prices or location actually moved — so this is a whole-row overwrite.
+                    //
+                    // Unlike the boards above there IS a remove: a vendor is dismissed, expires, or
+                    // its owner switches off the in-game Vendor Search flag, and any of those must
+                    // take the shop off the site. The last of the three is a privacy control, so
+                    // dropping the row promptly is the point rather than housekeeping.
+                    "vendor.listing" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            let loc = ev.value.get("location");
+                            let field = |k: &str| loc.and_then(|l| l.get(k));
+                            if let Err(e) = event_store
+                                .upsert_vendor(
+                                    serial,
+                                    ev.value.get("shopName").and_then(|v| v.as_str()),
+                                    ev.value.get("ownerName").and_then(|v| v.as_str()),
+                                    field("map").and_then(|v| v.as_str()),
+                                    field("x").and_then(|v| v.as_i64()),
+                                    field("y").and_then(|v| v.as_i64()),
+                                    field("region").and_then(|v| v.as_str()),
+                                    ev.value.get("count").and_then(|v| v.as_i64()),
+                                    &text,
+                                    t,
+                                )
+                                .await
+                            {
+                                tracing::warn!(error = %e, "failed to upsert vendor listing");
+                            }
+                        }
+                    }
+                    "vendor.listing.remove" => {
+                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
+                            if let Err(e) = event_store.delete_vendor(serial).await {
+                                tracing::warn!(error = %e, "failed to remove vendor listing");
+                            }
+                        }
+                    }
+                    // Shard ruleset (Protocol 3.0): a singleton projection. The shard re-emits
+                    // world.ruleset on every connect, so this row is simply overwritten; `rev`
+                    // lets a reader tell a re-send from an actual config change.
+                    "world.ruleset" => {
+                        if let Err(e) = event_store
+                            .upsert_ruleset(ev.value.get("rev").and_then(|r| r.as_str()), &text, t)
+                            .await
+                        {
+                            tracing::warn!(error = %e, "failed to upsert ruleset");
+                        }
+                    }
+                    _ => {}
+                }
+            }
+
+            // On a shard (re)connect, re-push the stored external news: the shard rebuilds
+            // TownCryerSystem.NewsEntries from scratch each boot and does not persist ours. Replay
+            // with announce=false so a restart does not re-proclaim every article at once. news.add
+            // is idempotent by id, so replaying to a still-populated shard is harmless.
+            if ev.kind == "server.hello" {
+                // A (re)connected shard restarts every roster from `seq` 0, so any half-received
+                // one belongs to the previous connection and can never be completed.
+                roster_parts.clear();
+
+                match event_store.news_all().await {
+                    Ok(items) => {
+                        for mut item in items {
+                            if let Some(obj) = item.as_object_mut() {
+                                obj.insert("announce".to_string(), serde_json::json!(false));
+                            }
+                            if !replay_handle.send(item.to_string()).await {
+                                break; // shard went away mid-replay
+                            }
+                        }
+                    }
+                    Err(e) => tracing::warn!(error = %e, "news replay: could not read stored news"),
+                }
+            }
+
+            let _ = feed_tx.send(ev.value.to_string());
+        }
+    });
+
+    // Heartbeat to the shard, exercising the command path.
+    let ping_handle = handle.clone();
+    tokio::spawn(async move {
+        loop {
+            tokio::time::sleep(std::time::Duration::from_secs(15)).await;
+            if ping_handle.is_connected().await {
+                let _ = ping_handle
+                    .send(r#"{"kind":"ping","id":"sidecar-heartbeat"}"#.to_string())
+                    .await;
+            }
+        }
+    });
+
+    // Everything that can fail at startup has now either failed or succeeded: the shard port is
+    // bound and the store is open. A supervisor may call this "started".
+    ready();
+
+    shutdown.await;
+    info!("shutting down");
+    Ok(())
+}
+
+pub fn now_ms() -> i64 {
+    use std::time::{SystemTime, UNIX_EPOCH};
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|d| d.as_millis() as i64)
+        .unwrap_or(0)
+}
+
+/// A guild roster that has arrived in part: the `seq` expected next, and what has accumulated.
+struct RosterParts {
+    next_seq: i64,
+    members: Vec<Value>,
+}
+
+/// Refuses to accumulate a roster past this many members. The shard caps its own frames, so
+/// exceeding this means a shard that is buggy or not what it claims to be — and the one thing this
+/// buffer must not do is grow without bound on its say-so.
+const MAX_ROSTER_MEMBERS: usize = 50_000;
+
+/// Reassembles a `guild.roster` that the shard split across frames, returning the whole member list
+/// once the final frame arrives and `None` while one is still incomplete.
+///
+/// Reassembly happens **here, in memory, before the store** rather than by appending to the
+/// `members` column, for two reasons. Appending would make the write a read-modify-write — the exact
+/// thing the two-column board design exists to avoid — and it would publish a torn roster: a reader
+/// hitting `GET /guilds` between frames would see a partial member list as though it were the truth.
+/// Buffering keeps the store's write a single atomic upsert of a complete roster.
+///
+/// This is transport-level reassembly, not domain state: it is the same category of work as turning
+/// bytes into a line, and it holds nothing once a roster is complete. That is what keeps it
+/// compatible with the sidecar being a forwarder.
+///
+/// The ordinary case — a guild inside the shard's per-line cap, which is every realistic one —
+/// arrives as `seq` 0 with `more` false and is returned immediately without ever touching the map.
+fn accumulate_roster(
+    parts: &mut HashMap<i64, RosterParts>,
+    id: i64,
+    seq: i64,
+    more: bool,
+    members: Vec<Value>,
+) -> Option<Vec<Value>> {
+    if seq == 0 {
+        // A fresh roster supersedes any partial one: the shard restarts at 0 every time it emits,
+        // so a leftover buffer is from an emission that was interrupted and will never finish.
+        parts.remove(&id);
+
+        if !more {
+            return Some(members);
+        }
+
+        parts.insert(
+            id,
+            RosterParts {
+                next_seq: 1,
+                members,
+            },
+        );
+        return None;
+    }
+
+    let entry = match parts.get_mut(&id) {
+        Some(entry) => entry,
+        // A continuation with nothing to continue: the sidecar started, or the shard reconnected,
+        // midway through an emission. Dropping it is right — the next full roster is complete.
+        None => {
+            tracing::debug!(
+                guild = id,
+                seq,
+                "roster continuation with no start; ignoring"
+            );
+            return None;
+        }
+    };
+
+    if entry.next_seq != seq {
+        tracing::warn!(
+            guild = id,
+            expected = entry.next_seq,
+            got = seq,
+            "roster frames out of order; discarding the partial roster"
+        );
+        parts.remove(&id);
+        return None;
+    }
+
+    entry.members.extend(members);
+
+    if entry.members.len() > MAX_ROSTER_MEMBERS {
+        tracing::warn!(
+            guild = id,
+            len = entry.members.len(),
+            "roster exceeded the reassembly cap; discarding"
+        );
+        parts.remove(&id);
+        return None;
+    }
+
+    if more {
+        entry.next_seq = seq + 1;
+        return None;
+    }
+
+    parts.remove(&id).map(|done| done.members)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn members(names: &[&str]) -> Vec<Value> {
+        names
+            .iter()
+            .map(|n| serde_json::json!({"name": n}))
+            .collect()
+    }
+
+    fn names(vs: &[Value]) -> Vec<String> {
+        vs.iter()
+            .map(|v| v["name"].as_str().unwrap_or_default().to_string())
+            .collect()
+    }
+
+    #[test]
+    fn a_single_frame_roster_is_returned_immediately() {
+        // Every realistic guild takes this path, and it must not depend on the buffer at all.
+        let mut parts = HashMap::new();
+        let out = accumulate_roster(&mut parts, 1, 0, false, members(&["Ada", "Bo"]));
+
+        assert_eq!(names(&out.expect("complete")), ["Ada", "Bo"]);
+        assert!(parts.is_empty(), "nothing should be buffered");
+    }
+
+    #[test]
+    fn a_chunked_roster_reassembles_in_order() {
+        // The case the live rig caught: without this, only the final frame survived and a
+        // 155-member guild appeared on the board with 3 members.
+        let mut parts = HashMap::new();
+
+        assert!(accumulate_roster(&mut parts, 1, 0, true, members(&["Ada"])).is_none());
+        assert!(accumulate_roster(&mut parts, 1, 1, true, members(&["Bo"])).is_none());
+        let out = accumulate_roster(&mut parts, 1, 2, false, members(&["Cy"]));
+
+        assert_eq!(names(&out.expect("complete")), ["Ada", "Bo", "Cy"]);
+        assert!(parts.is_empty(), "buffer is released once complete");
+    }
+
+    #[test]
+    fn a_restarted_roster_supersedes_a_partial_one() {
+        // A shard that reconnects mid-emission starts again at seq 0. The abandoned frames must not
+        // end up spliced onto the front of the new roster.
+        let mut parts = HashMap::new();
+
+        assert!(accumulate_roster(&mut parts, 1, 0, true, members(&["Stale"])).is_none());
+        let out = accumulate_roster(&mut parts, 1, 0, false, members(&["Fresh"]));
+
+        assert_eq!(names(&out.expect("complete")), ["Fresh"]);
+    }
+
+    #[test]
+    fn an_out_of_order_frame_discards_the_partial_roster() {
+        // Better to publish nothing and wait for the next full emission than to store a roster with
+        // a hole in it that nothing downstream could detect.
+        let mut parts = HashMap::new();
+
+        assert!(accumulate_roster(&mut parts, 1, 0, true, members(&["Ada"])).is_none());
+        assert!(accumulate_roster(&mut parts, 1, 2, false, members(&["Skipped"])).is_none());
+        assert!(parts.is_empty());
+    }
+
+    #[test]
+    fn a_continuation_with_no_start_is_ignored() {
+        // The sidecar restarting midway through a shard's emission.
+        let mut parts = HashMap::new();
+
+        assert!(accumulate_roster(&mut parts, 1, 3, false, members(&["Orphan"])).is_none());
+        assert!(parts.is_empty());
+    }
+
+    #[test]
+    fn two_guilds_reassemble_independently() {
+        // Rosters for different guilds interleave freely — the sweep emits one guild after another
+        // and nothing serialises them on the wire.
+        let mut parts = HashMap::new();
+
+        assert!(accumulate_roster(&mut parts, 1, 0, true, members(&["A1"])).is_none());
+        assert!(accumulate_roster(&mut parts, 2, 0, true, members(&["B1"])).is_none());
+        let g2 = accumulate_roster(&mut parts, 2, 1, false, members(&["B2"]));
+        let g1 = accumulate_roster(&mut parts, 1, 1, false, members(&["A2"]));
+
+        assert_eq!(names(&g2.expect("guild 2")), ["B1", "B2"]);
+        assert_eq!(names(&g1.expect("guild 1")), ["A1", "A2"]);
+    }
+
+    #[test]
+    fn an_empty_roster_is_a_complete_roster() {
+        // A guild whose last member left emits one frame with an empty array. Treating that as
+        // "nothing to store" would leave the board showing the roster it had before.
+        let mut parts = HashMap::new();
+        let out = accumulate_roster(&mut parts, 1, 0, false, vec![]);
+
+        assert_eq!(out.expect("complete").len(), 0);
+    }
+}

sidecar/src/main.rs

@@ -1,21 +1,37 @@
 //! uo-link sidecar.
 //!
-//! Terminates the loopback link to the ServUO shard and exposes a website-facing HTTP surface. So
-//! far: the shard link (bidirectional) and a WebSocket live feed. REST queries and SQLite come next.
+//! Terminates the loopback link to the ServUO shard and exposes a website-facing HTTP surface: the
+//! shard link (bidirectional), a WebSocket live feed, and REST queries backed by SQLite.
+//!
+//! # Layout
+//!
+//! `main` does argument handling and nothing else; the sidecar proper lives in [`app`] and is the
+//! same code on every platform. Only *how the process is started and stopped* is
+//! platform-specific:
+//!
+//! ```text
+//!   systemd ──▶ main ──▶ unix::run ─────────────────────────┐
+//!                                                           ├──▶ app::run
+//!   SCM ─────▶ main ──▶ windows::run ──▶ ServiceMain ───────┘
+//!                                    └─▶ console fallback ──┘
+//! ```
+//!
+//! The Windows half is not optional politeness: the SCM refuses to supervise a program that does
+//! not speak its startup handshake (see [`windows`]). The platform modules are gated with `#[cfg]`
+//! and their dependencies are declared per target, so none of it reaches a Linux build.
 
+mod app;
 mod cli;
 mod config;
 mod rpc;
 mod shard;
 mod store;
+#[cfg(unix)]
+mod unix;
 mod web;
+#[cfg(windows)]
+mod windows;
 
-use std::sync::atomic::AtomicI64;
-use std::sync::Arc;
-use std::time::Instant;
-
-use tokio::sync::{broadcast, mpsc};
-use tracing::info;
 use tracing_subscriber::EnvFilter;
 
 /// Wire-protocol version between the website and the sidecar. Bump this whenever an event or
@@ -30,10 +46,90 @@ use tracing_subscriber::EnvFilter;
 /// `vendor.listing.remove`, with the `GET /ruleset`, `/points` and `/market` reads that serve them
 /// from the store. Same shape as the v2 bump — the kinds are additive, the endpoints are not — and
 /// there is deliberately no feature-negotiation array: v3 implies all three kinds.
-pub const PROTOCOL_VERSION: u32 = 3;
+///
+/// v4 (Protocol 4): adds `guild.roster` and `guild.leave`, giving the guild board a real member list
+/// instead of the member *count* that was all v2 could express. Additive in the same way again — the
+/// kinds are new, `GET /guilds` grows a `roster` key, and nothing existing changed shape. This is the
+/// first bump that also needed a **store migration** (`guilds.members`), because it is the first to
+/// add a column to a table that already exists rather than a whole new table; see `store::migrate`.
+///
+/// v5 (Protocol 5): three enrichments that are additive in the same way again, bumped together
+/// rather than one at a time because a protocol bump is not cheap here — it costs a sidecar
+/// release, a republished bundle and an operator update on every shard, so a field left out costs
+/// a whole second round of that rather than a follow-up commit. They are:
+///
+///   * `house.decay` gains `ownerName` and a decay SCHEDULE — `nextStage`, `decayPeriodSec`,
+///     `dynamicDecay`, and `estimatedCollapse` only where it is exactly knowable (at IDOC under
+///     dynamic decay; at any stage under static decay, which has no randomness to wait out).
+///   * `vendor.listing` gains `ownerAcct` — without which the frame names an owner nobody can
+///     resolve to a person — and a `fees` object carrying the charge, the funds, the pay interval
+///     and the resolved `dismissalAt`.
+///   * `account.login.result` is a NEW kind: the verdict of a login, which the pre-existing
+///     `account.login.attempt` structurally cannot carry (its EventSink fires before the auth
+///     decision is made).
+///
+/// **No store migration this time**, unlike v4. Every frame is persisted whole and the board tables
+/// index only the columns they already had, so the new fields ride inside the stored JSON and the
+/// new kind lands in `events` like any other. That is the dumb-forwarder property doing its job:
+/// the sidecar defines no schema for a frame's contents and so needs no change when they grow.
+///
+/// v6 (Protocol 6): the first bump that is about a GUARANTEE rather than about data, and the first
+/// the sidecar mostly gets for free. Two things:
+///
+///   * **`idempotencyKey` on inbound commands.** A command that carries one is executed by the shard
+///     at most once; a repeat is answered with the original reply rather than re-run. That is what
+///     makes a world-writing verb retryable at all — until now a lost acknowledgement was
+///     indistinguishable from a command that never applied, so the website had to declare every
+///     write un-retryable and accept losing one rather than risk doubling it. The sidecar's part is
+///     to CARRY the key (it rides in the command body, which every write endpoint already passes
+///     through verbatim) and to understand the one new answer the shard can now give: `bridge.busy`,
+///     meaning a command under that key is still in flight. See `web::respond`.
+///   * **`champ.boss.killed` is a new kind**: a champion's defeat, with the damage table only the
+///     shard ever sees. It was previously inferable from `champ.update` going `bossUp` true then
+///     false alongside a nearby `mob.killed`, which is fragile and says nothing about who did the
+///     work. It lands in `events` and on the feed like any other kind, with no code here at all —
+///     the dumb-forwarder property again.
+///
+/// **No store migration.** Nothing gains a column; the new kind is persisted whole like every other.
+///
+/// # Protocol 8 — the Asset Bridge (docs/link/v8.md)
+///
+/// The shard starts sending the operator's own **client assets** over this link: the cliloc string
+/// table, creature and item art, player models. The point is that an operator stops having to run
+/// a GUI converter on a desktop to make their site render a bestiary, and the shard is the only
+/// host that already has the client files — a ServUO server cannot boot without them.
+///
+/// Phase 1 is the transport, and the sidecar's share of it is three things:
+///
+///   * **A new command family, `assets.*`, forwarded verbatim** like every other. The first of them
+///     is `assets.sources` — stage 1 of the import gate: what the client files currently are, and
+///     what version of the shard's extractor would read them. No pixels cross on this call.
+///   * **An inbound line cap** — [`shard::MAX_INBOUND_LINE_BYTES`]. This is the one change that is
+///     not additive. `read_line` had no bound at all, which was survivable while the shard had no
+///     reason to send a large line; protocol 8 gives it one deliberately, and an unbounded read
+///     facing a component that now sends megabytes is a memory-exhaustion shape we would be
+///     inventing ourselves.
+///   * **Nothing else.** Assets ride the request/reply path, so `rpc::try_route` consumes them
+///     before `app.rs` can persist them to the store and fan them out to every WebSocket
+///     subscriber — which is what keeps a 512 KiB reply from being written to SQLite and broadcast
+///     to every connected client. The dumb-forwarder property is doing real work here: the sidecar
+///     does not know what an asset is, and must not learn.
+///
+/// Phase 2 adds the first family that actually carries content: **`cliloc.table`**, served at
+/// `GET /cliloc`. It pages — the shard cuts at a byte budget and the caller echoes a cursor back —
+/// and the sidecar forwards it without keeping any of it, which matters more here than usual: the
+/// payload is five megabytes of EA's strings out of the operator's own client, and the one copy of
+/// it that should exist is the one the website imports. That phase also gave `assets.error` a
+/// `code`, so the status a refusal maps to stops depending on the wording of a human-facing
+/// sentence (see [`web::asset_error_status`]).
+///
+/// **No store migration**, again: nothing on this plane is an event, so nothing is persisted.
+pub const PROTOCOL_VERSION: u32 = 8;
 
-#[tokio::main]
-async fn main() -> anyhow::Result<()> {
+// Not `#[tokio::main]`: on Windows the SCM dispatcher takes over this thread and starts the runtime
+// itself, on its own thread, once the service actually begins. The runtime is built by whichever
+// platform module ends up running.
+fn main() -> anyhow::Result<()> {
     let args = match cli::parse(std::env::args().skip(1)) {
         Ok(args) => args,
         Err(msg) => {
@@ -66,299 +162,15 @@ async fn main() -> anyhow::Result<()> {
         cli::Mode::Run => {}
     }
 
-    init_tracing();
-    info!("uo-link sidecar starting");
+    #[cfg(windows)]
+    return windows::run(args.config.as_deref());
 
-    let loaded = config::Config::load(args.config.as_deref())?;
-    let cfg = loaded.cfg;
-    info!(
-        config = %loaded.path.display(),
-        shard = %cfg.shard.bind,
-        web = %cfg.web.bind,
-        db = %cfg.store.path,
-        auth = cfg.auth_required(),
-        "configuration loaded"
-    );
-
-    // Shard link: events in, commands out.
-    let (event_tx, mut event_rx) = mpsc::unbounded_channel::<shard::ShardEvent>();
-    let handle = shard::serve(&cfg.shard.bind, event_tx).await?;
-
-    // Live feed: every shard event fans out to all connected website WebSocket clients.
-    let (bcast_tx, _) = broadcast::channel::<String>(1024);
-
-    // Request/reply correlation for REST queries.
-    let rpc = rpc::Rpc::new();
-
-    // Durable store: event history, economy series, cached profiles, link map.
-    let store = store::Store::open(&cfg.store.path).await?;
-
-    // Health/observability state.
-    let started = Instant::now();
-    let last_event = Arc::new(AtomicI64::new(0));
-
-    // Website-facing HTTP server.
-    let web_state = web::AppState {
-        events: bcast_tx.clone(),
-        shard: handle.clone(),
-        rpc: rpc.clone(),
-        store: store.clone(),
-        token: Arc::new(cfg.web.auth_token.clone()),
-        started,
-        last_event: last_event.clone(),
-    };
-    let web_bind = cfg.web.bind.clone();
-    tokio::spawn(async move {
-        if let Err(e) = web::serve(&web_bind, web_state).await {
-            tracing::error!(error = %e, "web server exited");
-        }
-    });
-
-    // Event loop: a line that correlates to a pending REST call is a reply — route it to the
-    // waiting caller and stop. Everything else is a live event: log it, persist it, broadcast it.
-    let feed_tx = bcast_tx.clone();
-    let route_rpc = rpc.clone();
-    let event_store = store.clone();
-    let last_event_ts = last_event.clone();
-    let replay_handle = handle.clone(); // re-push external news to the shard on (re)connect
-    let mut total: u64 = 0;
-    tokio::spawn(async move {
-        while let Some(ev) = event_rx.recv().await {
-            // Any line from the shard — including pong heartbeats — is a sign of life.
-            last_event_ts.store(now_ms(), std::sync::atomic::Ordering::Relaxed);
-
-            if route_rpc.try_route(&ev.value).await {
-                continue; // consumed as a reply
+    #[cfg(unix)]
+    return unix::run(args.config.as_deref());
 }
 
-            total += 1;
-            match ev.kind.as_str() {
-                "server.hello" | "mob.login" | "mob.logout" | "player.death" | "vendor.sale"
-                | "house.decay" | "link.request" => {
-                    info!(kind = %ev.kind, n = total, "{}", ev.value);
-                }
-                _ => tracing::debug!(kind = %ev.kind, n = total, "{}", ev.value),
-            }
-
-            // Persist, then broadcast. `pong` and `ws.hello` are ephemeral chatter, not history.
-            if ev.kind != "pong" {
-                let t = ev
-                    .value
-                    .get("t")
-                    .and_then(|v| v.as_i64())
-                    .unwrap_or_else(now_ms);
-                let text = ev.value.to_string();
-                if let Err(e) = event_store.insert_event(t, &ev.kind, &text).await {
-                    tracing::warn!(error = %e, "failed to persist event");
-                }
-
-                // The champ board is a live projection: champ.update folds in the latest state (one
-                // row per spawn), champ.remove drops a spawn that despawned or was slain.
-                match ev.kind.as_str() {
-                    "champ.update" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store
-                                .upsert_champ(
-                                    serial,
-                                    ev.value.get("status").and_then(|s| s.as_str()),
-                                    ev.value.get("name").and_then(|n| n.as_str()),
-                                    &text,
-                                    t,
-                                )
-                                .await
-                            {
-                                tracing::warn!(error = %e, "failed to upsert champ board");
-                            }
-                        }
-                    }
-                    "champ.remove" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store.delete_champ(serial).await {
-                                tracing::warn!(error = %e, "failed to remove champ board row");
-                            }
-                        }
-                    }
-                    // Guild board (Protocol 2.0): guild.update folds in the latest roster (one row
-                    // per guild id); guild.remove drops a disbanded guild.
-                    "guild.update" => {
-                        if let Some(id) = ev.value.get("id").and_then(|v| v.as_i64()) {
-                            if let Err(e) = event_store
-                                .upsert_guild(
-                                    id,
-                                    ev.value.get("name").and_then(|n| n.as_str()),
-                                    &text,
-                                    t,
-                                )
-                                .await
-                            {
-                                tracing::warn!(error = %e, "failed to upsert guild board");
-                            }
-                        }
-                    }
-                    "guild.remove" => {
-                        if let Some(id) = ev.value.get("id").and_then(|v| v.as_i64()) {
-                            if let Err(e) = event_store.delete_guild(id).await {
-                                tracing::warn!(error = %e, "failed to remove guild board row");
-                            }
-                        }
-                    }
-                    // Governor board (Protocol 2.0): city.update folds in each city's latest
-                    // governance state (one row per city).
-                    "city.update" => {
-                        if let Some(city) = ev.value.get("city").and_then(|c| c.as_str()) {
-                            if let Err(e) = event_store.upsert_governor(city, &text, t).await {
-                                tracing::warn!(error = %e, "failed to upsert governor board");
-                            }
-                        }
-                    }
-                    // House registry (Protocol 2.0): house.update folds in each house's latest state
-                    // (one row per serial); house.remove drops a demolished/traded house.
-                    "house.update" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store
-                                .upsert_house(
-                                    serial,
-                                    ev.value.get("name").and_then(|n| n.as_str()),
-                                    &text,
-                                    t,
-                                )
-                                .await
-                            {
-                                tracing::warn!(error = %e, "failed to upsert house registry");
-                            }
-                        }
-                    }
-                    "house.remove" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store.delete_house(serial).await {
-                                tracing::warn!(error = %e, "failed to remove house registry row");
-                            }
-                        }
-                    }
-                    // Points/loyalty boards (Protocol 3.0): one row per point system, keyed by
-                    // the shard's own PointsType name. The plugin only emits a system whose top N
-                    // actually moved, so this is a sparse stream of overwrites — and there is no
-                    // `points.remove` to handle, because the shard's set of systems is fixed at
-                    // startup and cannot shrink.
-                    "points.board" => {
-                        if let Some(system) = ev.value.get("system").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store
-                                .upsert_points_board(
-                                    system,
-                                    ev.value.get("nameString").and_then(|n| n.as_str()),
-                                    &text,
-                                    t,
-                                )
-                                .await
-                            {
-                                tracing::warn!(error = %e, "failed to upsert points board");
-                            }
-                        }
-                    }
-                    // Player-vendor market index (Protocol 3.0). Each frame is authoritative for
-                    // one vendor — the shard's round-robin sweep only emits a shop whose contents,
-                    // prices or location actually moved — so this is a whole-row overwrite.
-                    //
-                    // Unlike the boards above there IS a remove: a vendor is dismissed, expires, or
-                    // its owner switches off the in-game Vendor Search flag, and any of those must
-                    // take the shop off the site. The last of the three is a privacy control, so
-                    // dropping the row promptly is the point rather than housekeeping.
-                    "vendor.listing" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            let loc = ev.value.get("location");
-                            let field = |k: &str| loc.and_then(|l| l.get(k));
-                            if let Err(e) = event_store
-                                .upsert_vendor(
-                                    serial,
-                                    ev.value.get("shopName").and_then(|v| v.as_str()),
-                                    ev.value.get("ownerName").and_then(|v| v.as_str()),
-                                    field("map").and_then(|v| v.as_str()),
-                                    field("x").and_then(|v| v.as_i64()),
-                                    field("y").and_then(|v| v.as_i64()),
-                                    field("region").and_then(|v| v.as_str()),
-                                    ev.value.get("count").and_then(|v| v.as_i64()),
-                                    &text,
-                                    t,
-                                )
-                                .await
-                            {
-                                tracing::warn!(error = %e, "failed to upsert vendor listing");
-                            }
-                        }
-                    }
-                    "vendor.listing.remove" => {
-                        if let Some(serial) = ev.value.get("serial").and_then(|s| s.as_str()) {
-                            if let Err(e) = event_store.delete_vendor(serial).await {
-                                tracing::warn!(error = %e, "failed to remove vendor listing");
-                            }
-                        }
-                    }
-                    // Shard ruleset (Protocol 3.0): a singleton projection. The shard re-emits
-                    // world.ruleset on every connect, so this row is simply overwritten; `rev`
-                    // lets a reader tell a re-send from an actual config change.
-                    "world.ruleset" => {
-                        if let Err(e) = event_store
-                            .upsert_ruleset(ev.value.get("rev").and_then(|r| r.as_str()), &text, t)
-                            .await
-                        {
-                            tracing::warn!(error = %e, "failed to upsert ruleset");
-                        }
-                    }
-                    _ => {}
-                }
-            }
-
-            // On a shard (re)connect, re-push the stored external news: the shard rebuilds
-            // TownCryerSystem.NewsEntries from scratch each boot and does not persist ours. Replay
-            // with announce=false so a restart does not re-proclaim every article at once. news.add
-            // is idempotent by id, so replaying to a still-populated shard is harmless.
-            if ev.kind == "server.hello" {
-                match event_store.news_all().await {
-                    Ok(items) => {
-                        for mut item in items {
-                            if let Some(obj) = item.as_object_mut() {
-                                obj.insert("announce".to_string(), serde_json::json!(false));
-                            }
-                            if !replay_handle.send(item.to_string()).await {
-                                break; // shard went away mid-replay
-                            }
-                        }
-                    }
-                    Err(e) => tracing::warn!(error = %e, "news replay: could not read stored news"),
-                }
-            }
-
-            let _ = feed_tx.send(ev.value.to_string());
-        }
-    });
-
-    // Heartbeat to the shard, exercising the command path.
-    let ping_handle = handle.clone();
-    tokio::spawn(async move {
-        loop {
-            tokio::time::sleep(std::time::Duration::from_secs(15)).await;
-            if ping_handle.is_connected().await {
-                let _ = ping_handle
-                    .send(r#"{"kind":"ping","id":"sidecar-heartbeat"}"#.to_string())
-                    .await;
-            }
-        }
-    });
-
-    tokio::signal::ctrl_c().await?;
-    info!("shutting down");
-    Ok(())
-}
-
-fn now_ms() -> i64 {
-    use std::time::{SystemTime, UNIX_EPOCH};
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map(|d| d.as_millis() as i64)
-        .unwrap_or(0)
-}
-
-fn init_tracing() {
+/// Logging for a foreground run: human-readable, on stdout.
+pub fn init_console_tracing() {
     tracing_subscriber::fmt()
         .with_env_filter(
             EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info")),

sidecar/src/shard.rs

@@ -7,15 +7,130 @@
 //! Framing is newline-delimited JSON, bidirectional: the shard sends events, we send commands. We
 //! accept one shard connection at a time and re-accept when it drops (the shard reconnects on its
 //! own, with a bounded backoff).
+//!
+//! Inbound lines are **capped** (see [`MAX_INBOUND_LINE_BYTES`]). Until protocol 8 they were not:
+//! `read_line` will buffer a line of any length, which was survivable only because the shard had
+//! never had a reason to send a large one. The Asset Bridge gives it one, so the gap had to close
+//! before it became a memory-exhaustion shape we invented ourselves.
 
 use std::sync::Arc;
 
 use serde_json::Value;
-use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::TcpListener;
 use tokio::sync::{mpsc, Mutex};
 use tracing::{info, warn};
 
+/// The longest line the sidecar will accept from the shard, in bytes.
+///
+/// Set above the largest legal batch rather than at it: the shard cuts a batch when the next item
+/// would take it past `Bridge.AssetBatchBytes` (512 KiB), and always admits the first item of a
+/// page even when that item alone is bigger than the budget — so one page can legitimately
+/// overshoot by one item. Doubling the budget to get this cap is what makes that overshoot safe
+/// instead of a dropped reply.
+///
+/// Over-long lines are **discarded, not buffered**, and the connection stays up. That is the same
+/// disposition `BridgeLink.cs` has always had for its own 1 MiB inbound cap in the other
+/// direction, and it is the right one here: a single malformed frame is not a reason to tear down
+/// a link that live events are flowing over. The dropped reply simply times out and is
+/// re-requested, which is safe because everything on the asset plane is idempotent.
+pub const MAX_INBOUND_LINE_BYTES: usize = 1024 * 1024;
+
+/// What one read off the shard socket produced.
+#[derive(Debug)]
+enum Line {
+    /// A complete line, within the cap.
+    Complete(String),
+    /// A line that ran past the cap. Carries how many bytes were thrown away, for the log.
+    TooLong(usize),
+    /// The shard closed the connection.
+    Eof,
+}
+
+/// A cancel-safe, capped, newline-delimited reader.
+///
+/// Every piece of state that must survive a partial read lives here rather than in a local,
+/// because this is polled inside a `tokio::select!`: the loop below drops the future whenever a
+/// command wins the race, and a `discarding` flag or a half-filled buffer held in a local would be
+/// lost with it. Losing the buffer corrupts the *next* line; losing `discarding` turns the tail of
+/// an over-long line into a line of its own. Both are silent.
+///
+/// The only await point is `fill_buf`, and nothing is consumed until after it returns, so a
+/// cancellation between the two can lose at most the wakeup.
+#[derive(Default)]
+struct LineReader {
+    buf: Vec<u8>,
+    discarding: bool,
+    discarded: usize,
+}
+
+impl LineReader {
+    async fn next<R: AsyncBufRead + Unpin>(&mut self, reader: &mut R) -> std::io::Result<Line> {
+        loop {
+            let consumed;
+            let outcome;
+
+            {
+                let available = reader.fill_buf().await?;
+
+                if available.is_empty() {
+                    return Ok(Line::Eof);
+                }
+
+                match available.iter().position(|&b| b == b'\n') {
+                    Some(at) => {
+                        consumed = at + 1;
+
+                        if self.discarding {
+                            // The tail of a line we already gave up on. Swallow it, terminator
+                            // included, and report the size once.
+                            self.discarded += at;
+                            let total = self.discarded;
+                            self.discarding = false;
+                            self.discarded = 0;
+                            outcome = Some(Line::TooLong(total));
+                        } else if self.buf.len() + at > MAX_INBOUND_LINE_BYTES {
+                            // The cap is reached only now, on the chunk that also holds the
+                            // terminator — so there is nothing left to discard.
+                            let total = self.buf.len() + at;
+                            self.buf.clear();
+                            outcome = Some(Line::TooLong(total));
+                        } else {
+                            self.buf.extend_from_slice(&available[..at]);
+                            let line = String::from_utf8_lossy(&self.buf).into_owned();
+                            self.buf.clear();
+                            outcome = Some(Line::Complete(line));
+                        }
+                    }
+                    None => {
+                        consumed = available.len();
+
+                        if self.discarding {
+                            self.discarded += consumed;
+                        } else if self.buf.len() + consumed > MAX_INBOUND_LINE_BYTES {
+                            // Refuse rather than buffer: this is the whole point of the cap.
+                            // Everything up to the next newline is now dropped on the floor.
+                            self.discarded = self.buf.len() + consumed;
+                            self.buf.clear();
+                            self.discarding = true;
+                        } else {
+                            self.buf.extend_from_slice(available);
+                        }
+
+                        outcome = None;
+                    }
+                }
+            }
+
+            reader.consume(consumed);
+
+            if let Some(line) = outcome {
+                return Ok(line);
+            }
+        }
+    }
+}
+
 /// An event line received from the shard, parsed. `kind` is lifted out for routing.
 #[derive(Debug, Clone)]
 pub struct ShardEvent {
@@ -112,16 +227,25 @@ async fn handle_connection(
     handle.set(Some(cmd_tx)).await;
 
     let mut reader = BufReader::new(read_half);
-    let mut line = String::new();
+    let mut lines = LineReader::default();
 
     loop {
         tokio::select! {
             // Inbound: a line from the shard.
-            result = reader.read_line(&mut line) => {
-                let n = result?;
-                if n == 0 {
-                    return Ok(()); // clean EOF: shard closed
+            result = lines.next(&mut reader) => {
+                match result? {
+                    Line::Eof => return Ok(()), // clean EOF: shard closed
+                    Line::TooLong(bytes) => {
+                        // Deliberately not a disconnect. See MAX_INBOUND_LINE_BYTES: a reply lost
+                        // this way times out on the caller's side and is re-requested, and tearing
+                        // the link down would take the live event feed with it.
+                        warn!(
+                            bytes,
+                            cap = MAX_INBOUND_LINE_BYTES,
+                            "inbound line over the cap; discarded"
+                        );
                     }
+                    Line::Complete(line) => {
                         let trimmed = line.trim_end();
                         if !trimmed.is_empty() {
                             match serde_json::from_str::<Value>(trimmed) {
@@ -136,7 +260,8 @@ async fn handle_connection(
                                 Err(e) => warn!(error = %e, line = %trimmed, "unparseable event"),
                             }
                         }
-                line.clear();
+                    }
+                }
             }
             // Outbound: a command to write to the shard.
             cmd = cmd_rx.recv() => {
@@ -152,3 +277,108 @@ async fn handle_connection(
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Drives `LineReader` over a byte slice, returning every outcome up to EOF.
+    async fn read_all(input: &[u8]) -> Vec<Line> {
+        let mut reader = BufReader::with_capacity(64, input);
+        let mut lines = LineReader::default();
+        let mut out = Vec::new();
+
+        loop {
+            match lines.next(&mut reader).await.unwrap() {
+                Line::Eof => break,
+                other => out.push(other),
+            }
+        }
+
+        out
+    }
+
+    fn complete(lines: &[Line]) -> Vec<&str> {
+        lines
+            .iter()
+            .filter_map(|l| match l {
+                Line::Complete(s) => Some(s.as_str()),
+                _ => None,
+            })
+            .collect()
+    }
+
+    #[tokio::test]
+    async fn splits_on_newlines() {
+        let lines = read_all(b"{\"a\":1}\n{\"b\":2}\n").await;
+        assert_eq!(complete(&lines), vec!["{\"a\":1}", "{\"b\":2}"]);
+    }
+
+    /// The reader's buffer is 64 bytes here, so every one of these lines spans several
+    /// `fill_buf` chunks. Reassembly across chunks is the thing `read_line` did for us.
+    #[tokio::test]
+    async fn reassembles_across_chunks() {
+        let long = "x".repeat(500);
+        let input = format!("{}\n{}\n", long, long);
+        let lines = read_all(input.as_bytes()).await;
+
+        assert_eq!(complete(&lines), vec![long.as_str(), long.as_str()]);
+    }
+
+    /// The cap itself. The over-long line must be reported and thrown away, and — the part that
+    /// actually matters — the line *after* it must still arrive intact. A reader that lost its
+    /// `discarding` flag would emit the tail of the oversized line as a line of its own.
+    #[tokio::test]
+    async fn refuses_an_over_long_line_and_recovers() {
+        let mut input = Vec::new();
+        input.extend_from_slice(&b"a".repeat(MAX_INBOUND_LINE_BYTES + 10));
+        input.push(b'\n');
+        input.extend_from_slice(b"{\"kind\":\"pong\"}\n");
+
+        let lines = read_all(&input).await;
+
+        assert_eq!(lines.len(), 2);
+        assert!(
+            matches!(lines[0], Line::TooLong(n) if n >= MAX_INBOUND_LINE_BYTES),
+            "expected TooLong, got {:?}",
+            lines[0]
+        );
+        assert_eq!(complete(&lines), vec!["{\"kind\":\"pong\"}"]);
+    }
+
+    /// A line of exactly the cap is legal; one byte more is not. Checking both sides is what says
+    /// the comparison is `>` rather than `>=`, which would silently cost a byte of the budget.
+    #[tokio::test]
+    async fn the_cap_is_inclusive() {
+        let at_cap = "b".repeat(MAX_INBOUND_LINE_BYTES);
+        let lines = read_all(format!("{}\n", at_cap).as_bytes()).await;
+        assert_eq!(complete(&lines).len(), 1);
+
+        let over = "b".repeat(MAX_INBOUND_LINE_BYTES + 1);
+        let lines = read_all(format!("{}\n", over).as_bytes()).await;
+        assert!(complete(&lines).is_empty());
+        assert!(matches!(lines[0], Line::TooLong(_)));
+    }
+
+    /// An over-long line whose terminator lands in the very chunk that crosses the cap: the
+    /// reader must not leave itself in `discarding` and eat the next line as well.
+    #[tokio::test]
+    async fn over_long_line_terminating_in_the_crossing_chunk() {
+        let mut input = Vec::new();
+        input.extend_from_slice(&b"c".repeat(MAX_INBOUND_LINE_BYTES + 1));
+        input.extend_from_slice(b"\n{\"kind\":\"pong\"}\n");
+
+        let lines = read_all(&input).await;
+
+        assert!(matches!(lines[0], Line::TooLong(_)));
+        assert_eq!(complete(&lines), vec!["{\"kind\":\"pong\"}"]);
+    }
+
+    /// A partial line at EOF is dropped rather than delivered half-parsed. The shard reconnects
+    /// and re-sends; half a JSON object is not something to hand to the event fan-out.
+    #[tokio::test]
+    async fn trailing_partial_line_at_eof_is_dropped() {
+        let lines = read_all(b"{\"a\":1}\n{\"b\":").await;
+        assert_eq!(complete(&lines), vec!["{\"a\":1}"]);
+    }
+}

sidecar/src/store.rs

@@ -45,6 +45,7 @@ impl Store {
             .await?;
 
         sqlx::query(SCHEMA).execute(&pool).await?;
+        migrate(&pool).await?;
         info!(%path, "store ready");
         Ok(Self { pool })
     }
@@ -236,12 +237,61 @@ impl Store {
         Ok(())
     }
 
+    /// Upserts one guild's member roster (Protocol 4), keyed by guild id, touching **only** the
+    /// `members` column.
+    ///
+    /// Deliberately not a write to `json`. That column holds the verbatim `guild.update` line, and a
+    /// roster arriving as its own event must not clobber the snapshot — name, abbreviation, leader,
+    /// online count — that `guild.update` owns. Splitting the two writers across two columns of one
+    /// row is what lets both be plain upserts: neither needs to read the other's value first, so
+    /// there is no read-modify-write and no ordering requirement between the two kinds.
+    ///
+    /// The `INSERT` half is not redundant: a roster can arrive before the first `guild.update` for a
+    /// guild, and the row it creates then carries `'{}'` until that update fills it in.
+    pub async fn upsert_guild_roster(
+        &self,
+        id: i64,
+        members_json: &str,
+        t: i64,
+    ) -> anyhow::Result<()> {
+        sqlx::query(
+            "INSERT INTO guilds (id, name, json, updated_t, members) VALUES (?, NULL, '{}', ?, ?)
+             ON CONFLICT(id) DO UPDATE SET members = excluded.members, updated_t = excluded.updated_t",
+        )
+        .bind(id)
+        .bind(t)
+        .bind(members_json)
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+
     /// The full guild board: every guild's latest snapshot, ordered by name.
+    ///
+    /// The roster is stored in its own column (see [`Self::upsert_guild_roster`]) and folded into
+    /// the projected object as `roster` here, at read time. A guild that has had a `guild.update`
+    /// but no `guild.roster` yet simply has no `roster` key, which is the honest representation of
+    /// "not known" and distinct from a guild whose roster is genuinely empty.
     pub async fn guilds_all(&self) -> anyhow::Result<Vec<Value>> {
-        let rows = sqlx::query("SELECT json FROM guilds ORDER BY name, id")
+        let rows = sqlx::query("SELECT json, members FROM guilds ORDER BY name, id")
             .fetch_all(&self.pool)
             .await?;
-        Ok(parse_json_column(rows))
+
+        Ok(rows
+            .into_iter()
+            .filter_map(|r| {
+                let mut v: Value = serde_json::from_str(&r.get::<String, _>("json")).ok()?;
+                let members: Option<String> = r.get("members");
+
+                if let (Some(obj), Some(raw)) = (v.as_object_mut(), members) {
+                    if let Ok(list) = serde_json::from_str::<Value>(&raw) {
+                        obj.insert("roster".into(), list);
+                    }
+                }
+
+                Some(v)
+            })
+            .collect())
     }
 
     // ---- governor board (Protocol 2.0) ----
@@ -513,6 +563,75 @@ impl Store {
     }
 }
 
+/// The schema version this build expects. Bump it, and add the matching arm to [`migrate`], for
+/// every change that `SCHEMA` alone cannot make to a database that already exists.
+const SCHEMA_VERSION: i64 = 1;
+
+/// Brings an existing database forward to [`SCHEMA_VERSION`].
+///
+/// `SCHEMA` is `CREATE TABLE IF NOT EXISTS` only, which is enough to *add a table* but cannot add a
+/// column to a table that is already there. Every schema change up to and including Protocol 3.0
+/// happened to add whole tables, so this never mattered and `ALTER TABLE` appears nowhere in this
+/// repo's history. `guilds.members` (Protocol 4) is the first column added to an existing table, so
+/// the mechanism has to exist now.
+///
+/// The version counter is SQLite's own `PRAGMA user_version`: an integer in the database header, so
+/// it needs no table of its own and cannot be separated from the file it describes. Each step runs
+/// in a transaction **together with** the bump that records it, so a step either lands completely or
+/// not at all, and an interrupted run resumes at the right place rather than re-applying half of one.
+///
+/// A failure here propagates and aborts startup, deliberately. A half-migrated store answers the
+/// website with confusing partial data, which is worse than being plainly absent — and the shard
+/// dials *out* to the sidecar, so a sidecar that refuses to start never stalls the game.
+async fn migrate(pool: &SqlitePool) -> anyhow::Result<()> {
+    let mut version: i64 = sqlx::query_scalar("PRAGMA user_version")
+        .fetch_one(pool)
+        .await?;
+
+    // A database written by a *newer* sidecar than this binary. This is not an error: every step
+    // here is additive, so a newer schema has only columns and tables an older reader ignores, and
+    // refusing to start would turn "roll the binary back" — a recovery path — into a dead end.
+    if version > SCHEMA_VERSION {
+        tracing::warn!(
+            found = version,
+            expected = SCHEMA_VERSION,
+            "store was written by a newer sidecar; continuing, as migrations are additive"
+        );
+        return Ok(());
+    }
+
+    while version < SCHEMA_VERSION {
+        let next = version + 1;
+        let mut tx = pool.begin().await?;
+
+        match next {
+            // Protocol 4: the guild board carries a member roster. Its own column rather than a
+            // field folded into `json`, because `json` holds the verbatim `guild.update` line and
+            // the two writers must not overwrite each other — see `upsert_guild_roster`.
+            1 => {
+                sqlx::query("ALTER TABLE guilds ADD COLUMN members TEXT")
+                    .execute(&mut *tx)
+                    .await?;
+            }
+            // Unreachable while SCHEMA_VERSION and this match are edited together, which is the
+            // point of failing loudly rather than silently leaving the counter short.
+            n => anyhow::bail!("no migration step defined for schema version {n}"),
+        }
+
+        // `PRAGMA` takes no bind parameters, so this is formatted — safe because `next` is an i64
+        // this loop produced, never anything from outside the process.
+        sqlx::query(&format!("PRAGMA user_version = {next}"))
+            .execute(&mut *tx)
+            .await?;
+
+        tx.commit().await?;
+        info!(version = next, "schema migration applied");
+        version = next;
+    }
+
+    Ok(())
+}
+
 fn parse_json_column(rows: Vec<sqlx::sqlite::SqliteRow>) -> Vec<Value> {
     rows.into_iter()
         .filter_map(|r| serde_json::from_str(&r.get::<String, _>("json")).ok())
@@ -611,3 +730,195 @@ CREATE TABLE IF NOT EXISTS ruleset (
     updated_t INTEGER NOT NULL
 );
 "#;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// A unique scratch database path. Matches `config`'s idiom — `std::env::temp_dir()` plus the
+    /// test name — so the cases stay independent under the parallel test runner.
+    fn scratch(name: &str) -> String {
+        let dir = std::env::temp_dir().join(format!("uo-link-store-test-{name}"));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).expect("create scratch dir");
+        dir.join("uo-link.db").to_string_lossy().into_owned()
+    }
+
+    /// The `guilds` table exactly as a pre-Protocol-4 sidecar left it: no `members` column, and
+    /// `user_version` still 0. This is the shape a real operator's database is in before an update,
+    /// and the only starting point where the migration does anything.
+    async fn legacy_db(path: &str) -> SqlitePool {
+        let pool = SqlitePoolOptions::new()
+            .max_connections(1)
+            .connect_with(
+                SqliteConnectOptions::new()
+                    .filename(path)
+                    .create_if_missing(true),
+            )
+            .await
+            .expect("open legacy db");
+
+        sqlx::query(
+            "CREATE TABLE guilds (
+                 id        INTEGER PRIMARY KEY,
+                 name      TEXT,
+                 json      TEXT NOT NULL,
+                 updated_t INTEGER NOT NULL
+             )",
+        )
+        .execute(&pool)
+        .await
+        .expect("create legacy guilds table");
+
+        pool.close().await;
+        pool
+    }
+
+    async fn user_version(store: &Store) -> i64 {
+        sqlx::query_scalar("PRAGMA user_version")
+            .fetch_one(&store.pool)
+            .await
+            .expect("read user_version")
+    }
+
+    async fn guild_columns(store: &Store) -> Vec<String> {
+        sqlx::query("PRAGMA table_info(guilds)")
+            .fetch_all(&store.pool)
+            .await
+            .expect("table_info")
+            .into_iter()
+            .map(|r| r.get::<String, _>("name"))
+            .collect()
+    }
+
+    #[tokio::test]
+    async fn an_existing_pre_protocol_4_database_gains_the_members_column() {
+        // The case that matters: `SCHEMA`'s CREATE TABLE IF NOT EXISTS is a no-op against a table
+        // that is already there, so without `migrate` this database would never get the column and
+        // every roster write would fail against a live install.
+        let path = scratch("legacy-upgrade");
+        legacy_db(&path).await;
+
+        let store = Store::open(&path).await.expect("open migrates");
+
+        assert!(
+            guild_columns(&store).await.contains(&"members".to_string()),
+            "the migration must add guilds.members to a database that already had the table"
+        );
+        assert_eq!(user_version(&store).await, SCHEMA_VERSION);
+    }
+
+    #[tokio::test]
+    async fn a_fresh_database_lands_at_the_current_version() {
+        let path = scratch("fresh");
+        let store = Store::open(&path).await.expect("open");
+
+        assert!(guild_columns(&store).await.contains(&"members".to_string()));
+        assert_eq!(user_version(&store).await, SCHEMA_VERSION);
+    }
+
+    #[tokio::test]
+    async fn reopening_an_already_migrated_database_is_a_no_op() {
+        // Every sidecar restart re-runs this path, so a second run must not attempt the ALTER again
+        // — which would fail with "duplicate column name" and, since a migration failure aborts
+        // startup, would leave the sidecar unable to start at all after its first upgrade.
+        let path = scratch("idempotent");
+        legacy_db(&path).await;
+
+        Store::open(&path).await.expect("first open");
+        let store = Store::open(&path).await.expect("second open must succeed");
+
+        assert_eq!(user_version(&store).await, SCHEMA_VERSION);
+    }
+
+    #[tokio::test]
+    async fn a_roster_does_not_clobber_the_guild_update_snapshot() {
+        // The invariant the two-column split exists to give. `json` holds the verbatim guild.update
+        // line; if a roster write touched it, name/abbr/online would vanish from the board.
+        let path = scratch("no-clobber");
+        let store = Store::open(&path).await.expect("open");
+
+        store
+            .upsert_guild(
+                7,
+                Some("The Cartographers"),
+                r#"{"kind":"guild.update","id":7,"name":"The Cartographers","abbr":"MAP","members":2,"online":1}"#,
+                100,
+            )
+            .await
+            .expect("upsert guild");
+
+        store
+            .upsert_guild_roster(
+                7,
+                r#"[{"serial":"0x1","name":"Ada"},{"serial":"0x2","name":"Bo"}]"#,
+                200,
+            )
+            .await
+            .expect("upsert roster");
+
+        let guilds = store.guilds_all().await.expect("read board");
+        assert_eq!(guilds.len(), 1);
+        let g = &guilds[0];
+
+        assert_eq!(
+            g["name"], "The Cartographers",
+            "guild.update's name survived"
+        );
+        assert_eq!(g["abbr"], "MAP", "guild.update's abbr survived");
+        assert_eq!(g["online"], 1, "guild.update's online count survived");
+        assert_eq!(g["roster"].as_array().expect("roster is an array").len(), 2);
+        assert_eq!(g["roster"][0]["name"], "Ada");
+    }
+
+    #[tokio::test]
+    async fn the_two_writers_are_order_independent() {
+        // A roster can arrive before the first guild.update for a guild — on a reconnect the shard
+        // re-emits both and nothing orders them. Neither write may depend on the other's row.
+        let path = scratch("either-order");
+        let store = Store::open(&path).await.expect("open");
+
+        store
+            .upsert_guild_roster(9, r#"[{"serial":"0x3","name":"Cy"}]"#, 100)
+            .await
+            .expect("roster first");
+        store
+            .upsert_guild(
+                9,
+                Some("Late Arrivals"),
+                r#"{"kind":"guild.update","id":9,"name":"Late Arrivals","abbr":"LTE"}"#,
+                200,
+            )
+            .await
+            .expect("update second");
+
+        let guilds = store.guilds_all().await.expect("read board");
+        assert_eq!(guilds.len(), 1, "one row, not two");
+        assert_eq!(guilds[0]["name"], "Late Arrivals");
+        assert_eq!(guilds[0]["roster"].as_array().expect("roster").len(), 1);
+    }
+
+    #[tokio::test]
+    async fn a_guild_with_no_roster_yet_has_no_roster_key() {
+        // "Not known" and "known to be empty" are different, and the board must not conflate them:
+        // a website reading `roster: []` would render an empty roster as fact.
+        let path = scratch("absent-roster");
+        let store = Store::open(&path).await.expect("open");
+
+        store
+            .upsert_guild(
+                11,
+                Some("Unswept"),
+                r#"{"kind":"guild.update","id":11,"name":"Unswept"}"#,
+                100,
+            )
+            .await
+            .expect("upsert guild");
+
+        let guilds = store.guilds_all().await.expect("read board");
+        assert!(
+            guilds[0].get("roster").is_none(),
+            "a guild with no roster event must not grow a roster key"
+        );
+    }
+}

sidecar/src/unix.rs

@@ -0,0 +1,41 @@
+//! Unix startup and shutdown.
+//!
+//! There is no supervisor protocol to speak: systemd starts the process, and stops it by sending
+//! `SIGTERM`. All this module does is translate the two signals that mean "stop" into the future
+//! [`crate::app::run`] waits on, so a `systemctl stop` unwinds the same way a Ctrl-C does instead
+//! of being killed by the default `SIGTERM` disposition mid-write.
+
+use tokio::signal::unix::{signal, SignalKind};
+
+pub fn run(config_path: Option<&str>) -> anyhow::Result<()> {
+    crate::init_console_tracing();
+
+    tokio::runtime::Runtime::new()?.block_on(crate::app::run(config_path, || {}, shutdown_signal()))
+}
+
+/// Resolves on the first `SIGINT` or `SIGTERM`.
+async fn shutdown_signal() {
+    // A failure to install a handler is not worth aborting a running sidecar for: fall back to
+    // pending, which leaves that signal's default disposition (terminate) in place.
+    let mut term = match signal(SignalKind::terminate()) {
+        Ok(s) => s,
+        Err(e) => {
+            tracing::warn!(error = %e, "could not listen for SIGTERM");
+            std::future::pending::<()>().await;
+            unreachable!()
+        }
+    };
+    let mut int = match signal(SignalKind::interrupt()) {
+        Ok(s) => s,
+        Err(e) => {
+            tracing::warn!(error = %e, "could not listen for SIGINT");
+            term.recv().await;
+            return;
+        }
+    };
+
+    tokio::select! {
+        _ = term.recv() => tracing::info!("SIGTERM received"),
+        _ = int.recv()  => tracing::info!("SIGINT received"),
+    }
+}

sidecar/src/windows.rs

@@ -0,0 +1,239 @@
+//! Windows startup and shutdown: the SCM handshake.
+//!
+//! Unlike systemd, the Windows Service Control Manager cannot supervise an arbitrary console
+//! program. A binary registered with `sc.exe create` has ~30 seconds to call
+//! `StartServiceCtrlDispatcher` and connect back to the SCM; one that never does is killed with
+//! **error 1053, "the service did not respond to the start request in a timely fashion"** — even
+//! though the process itself started perfectly and is sitting there serving traffic. That is the
+//! entire reason this module exists.
+//!
+//! ## One binary, two ways in
+//!
+//! The dispatcher is tried first and *failing is expected*: when the process was started from a
+//! shell rather than by the SCM, the connect fails with `ERROR_FAILED_SERVICE_CONTROLLER_CONNECT`
+//! (1063), and that — and only that — falls through to a normal foreground run. So
+//! `uo-link-sidecar.exe --config ...` stays an ordinary console app you can Ctrl-C, `cargo run`
+//! still works, and the same binary can be registered as a service with no `--service` flag for an
+//! operator to forget. Any other dispatcher error is a real failure and is reported.
+//!
+//! ## Logging goes to a file, because a service has no stdout
+//!
+//! Under the SCM there is no console attached, so the normal stdout subscriber writes into the
+//! void. In service mode the sidecar logs to a daily-rolled file next to its config instead
+//! (`uo-link-sidecar.YYYY-MM-DD.log`, seven kept). A service whose start fails leaves a reason
+//! behind rather than only an SCM error code.
+
+use std::ffi::OsString;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::OnceLock;
+use std::time::Duration;
+
+use tokio::sync::Notify;
+use tracing_subscriber::EnvFilter;
+use windows_service::service::{
+    ServiceControl, ServiceControlAccept, ServiceExitCode, ServiceState, ServiceStatus, ServiceType,
+};
+use windows_service::service_control_handler::{self, ServiceControlHandlerResult};
+use windows_service::{define_windows_service, service_dispatcher};
+
+/// Must match the name the installer registers (`installer/src/service.rs::WINDOWS_SERVICE`). For
+/// an own-process service the SCM ignores it, but a mismatch would be a trap for whoever converts
+/// this to a shared-process service later.
+pub const SERVICE_NAME: &str = "RunicGatewayLink";
+
+const SERVICE_TYPE: ServiceType = ServiceType::OWN_PROCESS;
+
+/// `ERROR_FAILED_SERVICE_CONTROLLER_CONNECT` — "this process was not started by the SCM", which is
+/// the normal answer when a human runs the binary.
+const ERROR_FAILED_SERVICE_CONTROLLER_CONNECT: i32 = 1063;
+
+/// `service_main` is called through an `extern "system"` trampoline and so can capture nothing.
+/// The parsed `--config` is handed over here instead of being re-parsed, so the service and a
+/// console run resolve their configuration through exactly the same code path.
+static CONFIG_PATH: OnceLock<Option<String>> = OnceLock::new();
+
+pub fn run(config_path: Option<&str>) -> anyhow::Result<()> {
+    let _ = CONFIG_PATH.set(config_path.map(str::to_string));
+
+    match service_dispatcher::start(SERVICE_NAME, ffi_service_main) {
+        Ok(()) => Ok(()),
+        // Not started by the SCM: this is a foreground run, which is not an error.
+        Err(windows_service::Error::Winapi(e))
+            if e.raw_os_error() == Some(ERROR_FAILED_SERVICE_CONTROLLER_CONNECT) =>
+        {
+            console_run(config_path)
+        }
+        Err(e) => Err(anyhow::Error::new(e)
+            .context("could not connect to the Windows service control manager")),
+    }
+}
+
+/// A normal foreground run: stdout logging, Ctrl-C to stop.
+fn console_run(config_path: Option<&str>) -> anyhow::Result<()> {
+    crate::init_console_tracing();
+    tokio::runtime::Runtime::new()?.block_on(crate::app::run(config_path, || {}, async {
+        let _ = tokio::signal::ctrl_c().await;
+    }))
+}
+
+define_windows_service!(ffi_service_main, service_main);
+
+fn service_main(_arguments: Vec<OsString>) {
+    // Arguments are deliberately ignored: for an own-process service the `binPath=` arguments
+    // arrive on the process command line and have already been parsed in `main`. What lands here
+    // is whatever was typed after `sc start`, which nothing in this deployment uses.
+    if let Err(e) = serve() {
+        // Nowhere left to report to but the log: the status handle is gone or was never obtained.
+        tracing::error!(error = %e, "service exited with an error");
+    }
+}
+
+fn serve() -> anyhow::Result<()> {
+    let config_path = CONFIG_PATH.get().cloned().flatten();
+    // Held for the life of the service: dropping the guard stops the background log writer.
+    let _log_guard = init_service_tracing(config_path.as_deref());
+
+    // The SCM calls the control handler on its own thread, so the stop signal crosses a thread
+    // boundary into the async world. `notify_one` stores a permit if nothing is waiting yet, so a
+    // stop that arrives during startup is not lost.
+    let stop = Arc::new(Notify::new());
+    let handler_stop = stop.clone();
+    let status_handle =
+        service_control_handler::register(SERVICE_NAME, move |control| match control {
+            ServiceControl::Interrogate => ServiceControlHandlerResult::NoError,
+            ServiceControl::Stop | ServiceControl::Shutdown => {
+                handler_stop.notify_one();
+                ServiceControlHandlerResult::NoError
+            }
+            _ => ServiceControlHandlerResult::NotImplemented,
+        })?;
+
+    // Registering the handler is the handshake 1053 was about. Everything after this point gets to
+    // take as long as it credibly needs, as long as the state keeps being reported.
+    status_handle.set_service_status(ServiceStatus {
+        service_type: SERVICE_TYPE,
+        current_state: ServiceState::StartPending,
+        controls_accepted: ServiceControlAccept::empty(),
+        exit_code: ServiceExitCode::Win32(0),
+        checkpoint: 0,
+        wait_hint: Duration::from_secs(30),
+        process_id: None,
+    })?;
+
+    let ready_handle = status_handle;
+    let result = tokio::runtime::Runtime::new()?.block_on(crate::app::run(
+        config_path.as_deref(),
+        // Reported only once the shard port is bound and the store is open, so a bad config or a
+        // taken port fails the *start* instead of flapping Running → Stopped a moment later.
+        move || {
+            let _ = ready_handle.set_service_status(ServiceStatus {
+                service_type: SERVICE_TYPE,
+                current_state: ServiceState::Running,
+                controls_accepted: ServiceControlAccept::STOP | ServiceControlAccept::SHUTDOWN,
+                exit_code: ServiceExitCode::Win32(0),
+                checkpoint: 0,
+                wait_hint: Duration::default(),
+                process_id: None,
+            });
+        },
+        async move { stop.notified().await },
+    ));
+
+    // A failed run must leave a nonzero SERVICE_EXIT_CODE behind: `sc query` reporting STOPPED with
+    // exit code 0 is what made the original failure look like a clean stop.
+    let exit_code = match &result {
+        Ok(()) => ServiceExitCode::Win32(0),
+        Err(e) => {
+            tracing::error!(error = %e, "sidecar failed");
+            ServiceExitCode::ServiceSpecific(1)
+        }
+    };
+    status_handle.set_service_status(ServiceStatus {
+        service_type: SERVICE_TYPE,
+        current_state: ServiceState::Stopped,
+        controls_accepted: ServiceControlAccept::empty(),
+        exit_code,
+        checkpoint: 0,
+        wait_hint: Duration::default(),
+        process_id: None,
+    })?;
+
+    result
+}
+
+/// Where the service writes its log: beside the config it was pointed at, which is the directory
+/// the installer already provisions and grants the service account write access to.
+fn log_dir(config_path: Option<&str>) -> PathBuf {
+    if let Some(parent) = config_path
+        .map(PathBuf::from)
+        .as_deref()
+        .and_then(|p| p.parent())
+        .filter(|p| !p.as_os_str().is_empty())
+    {
+        return parent.to_path_buf();
+    }
+    match std::env::var_os("ProgramData") {
+        Some(program_data) => PathBuf::from(program_data).join("RunicGateway"),
+        None => std::env::temp_dir(),
+    }
+}
+
+/// Returns `None` if the log file could not be opened — a service that cannot write a log is still
+/// a service worth running, and the SCM start must not fail over it.
+fn init_service_tracing(
+    config_path: Option<&str>,
+) -> Option<tracing_appender::non_blocking::WorkerGuard> {
+    let appender = tracing_appender::rolling::Builder::new()
+        .rotation(tracing_appender::rolling::Rotation::DAILY)
+        .filename_prefix("uo-link-sidecar")
+        .filename_suffix("log")
+        .max_log_files(7)
+        .build(log_dir(config_path))
+        .ok()?;
+
+    let (writer, guard) = tracing_appender::non_blocking(appender);
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info")),
+        )
+        .with_ansi(false) // a log file is not a terminal
+        .with_writer(writer)
+        .init();
+    Some(guard)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn log_dir_follows_the_config_file() {
+        assert_eq!(
+            log_dir(Some(r"C:\ProgramData\RunicGateway\sidecar.toml")),
+            PathBuf::from(r"C:\ProgramData\RunicGateway")
+        );
+    }
+
+    #[test]
+    fn a_bare_filename_does_not_become_the_filesystem_root() {
+        // `--config sidecar.toml` has a parent of "", which as a path means the root of the current
+        // drive — somewhere a service account cannot write. Fall back instead.
+        let dir = log_dir(Some("sidecar.toml"));
+        assert_ne!(dir, PathBuf::from(""));
+        assert!(dir.is_absolute(), "{}", dir.display());
+    }
+
+    #[test]
+    fn no_config_falls_back_to_program_data() {
+        let dir = log_dir(None);
+        assert!(dir.is_absolute(), "{}", dir.display());
+    }
+
+    #[test]
+    fn service_name_matches_the_installer() {
+        // installer/src/service.rs::WINDOWS_SERVICE. Kept as a literal on both sides — the two
+        // repos are released independently and do not share a crate.
+        assert_eq!(SERVICE_NAME, "RunicGatewayLink");
+    }
+}