diff --git a/CLAUDE.md b/CLAUDE.md
index a30c899d..5bf4d0f4 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -147,7 +147,7 @@ dotfiles/
 │   ├── mise/               # Global mise config for the no-Nix, non-admin account
 │                           #   (bootstrap.sh links it to ~/.config/mise; no module)
 │   └── venari/             # the rented box: twins of its /srv compose files (Soft Serve,
-│                           #   Ghost) and /etc drop-ins; nothing deploys them
+│                           #   Ghost, Convex) and /etc drop-ins; nothing deploys them
 ├── secrets/                # agenix/ragenix age-encrypted secrets
 ├── docker/                 # container notes (per-arch CLAUDE.md) + entrypoint
 ├── docs/solutions/         # documented solutions to past problems - bugs, practices,
diff --git a/tools/just/personal.just b/tools/just/personal.just
index 99bb673b..1fa3535a 100644
--- a/tools/just/personal.just
+++ b/tools/just/personal.just
@@ -36,6 +36,59 @@ ghost-tunnel:
 ghost-tunnel-close:
     @pkill -f 'ssh -fN venari-ghost' && echo "ghost tunnel closed" || echo "no ghost tunnel open"
 
+# Convex on venari (tools/venari/README.md, "Convex"): backend, HTTP actions and
+# dashboard listen on the box's loopback. These recipes use the `venari` and
+# `venari-root` aliases from ~/.ssh/config (README, "Access"; the box's address
+# is never in this repo). The forwards are inline, so unlike Ghost they need no
+# third alias. Laptop ports are the box's plus 10000 and must match
+# CONVEX_CLOUD_ORIGIN / CONVEX_SITE_ORIGIN in convex/docker-compose.yml.
+# The tunnel is an ssh control master on a socket, so `ssh -O check` / `-O exit`
+# find and close it on macOS and Linux alike - no pgrep/pkill, whose flags differ
+# (procps pgrep has no -q) and whose -f pattern also matches the calling shell.
+
+# open the Convex tunnel: 13210 -> API, 13211 -> HTTP actions, 16791 -> dashboard
+[group('personal')]
+convex-tunnel:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    sock="$HOME/.ssh/venari-convex.sock"
+    if ssh -o ControlPath="$sock" -O check venari 2>/dev/null; then
+        echo "convex tunnel already open"
+        exit 0
+    fi
+    rm -f "$sock"   # a master that died uncleanly leaves its socket behind
+    ssh -fN -o ControlMaster=yes -o ControlPath="$sock" -o ExitOnForwardFailure=yes \
+        -L 127.0.0.1:13210:127.0.0.1:3210 -L 127.0.0.1:13211:127.0.0.1:3211 -L 127.0.0.1:16791:127.0.0.1:6791 venari
+    echo "convex tunnel open: API 13210, HTTP actions 13211, dashboard 16791"
+
+# close the Convex tunnel
+[group('personal')]
+convex-tunnel-close:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    sock="$HOME/.ssh/venari-convex.sock"
+    if ssh -o ControlPath="$sock" -O exit venari 2>/dev/null; then
+        echo "convex tunnel closed"
+    else
+        rm -f "$sock"
+        echo "no convex tunnel open"
+    fi
+
+# print a new Convex admin key (each call differs; all stay valid until data/ is lost)
+[group('personal')]
+convex-admin-key:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    # Without pipefail a failed ssh or exec still exits 0 through `tail`, and the
+    # empty line or error text gets pasted into .env.local as the key. So the
+    # script also refuses anything not shaped like a key: <instance>|<hex>.
+    key=$(ssh venari-root 'cd /srv/convex && docker compose exec -T backend ./generate_admin_key.sh' | tail -n 1)
+    if [[ ! "$key" =~ ^[a-z0-9_-]+\|[0-9a-f]+$ ]]; then
+        echo "convex-admin-key: got no admin key from venari (output: '${key}')" >&2
+        exit 1
+    fi
+    printf '%s\n' "$key"
+
 # The box has two vCPUs and no Go, so the server binary is cross-compiled here
 # and only the static binary travels; the image on the box is Alpine plus that
 # file (tools/venari/ghost/server/Dockerfile).
diff --git a/tools/venari/README.md b/tools/venari/README.md
index 989bd786..ced513fc 100644
--- a/tools/venari/README.md
+++ b/tools/venari/README.md
@@ -22,6 +22,7 @@ the box is the running copy.
 | `ssh/soft-tunnel.authorized_keys` | `/var/lib/soft-tunnel/.ssh/authorized_keys` (root-owned, 644) |
 | `ghost/docker-compose.yml` | `/srv/ghost/docker-compose.yml`, with `.env` (from `.env.example`), `certs/`, `data/` and `server/` beside it |
 | `ghost/server/Dockerfile` | `/srv/ghost/server/Dockerfile`, next to the `ghost-server` binary it packages |
+| `convex/docker-compose.yml` | `/srv/convex/docker-compose.yml`, with `.env` (from `.env.example`) and `data/` beside it; its database is in Ghost's cluster |
 
 The dev-box side is `tools/mise/venari/` — the same arrangement felixia has,
 for the same reason: no Nix here either.
@@ -191,7 +192,153 @@ Then encrypt the box's `GHOST_API_KEY` into `secrets/personal/ghost-api-key.age`
 Not supported, and answered with 501: billing, spaces beyond the one, members,
 invites, shares, API-key management (the key is configuration). `ghost logs`
 returns an empty page. Backups: the cluster rides the provider's box backups,
-like Soft Serve's `data/`; Ghost databases are disposable by design.
+like Soft Serve's `data/`. Ghost databases are disposable by design, but the
+cluster also holds Convex's database, which is not (see "Convex").
+
+## Convex: a self-hosted app backend
+
+[Convex](https://www.convex.dev) is the backend create-epoch-app is built on:
+a document database, server functions (queries, mutations, actions), and live
+queries that push new results to subscribed clients. `/srv/convex/` runs the
+open-source backend and dashboard from
+[convex/convex-backend](https://github.com/convex/convex-backend)
+(`self-hosted/`), pinned to one revision for both images.
+
+It is not a replacement for Ghost, and Ghost is not one for it. Ghost hands out
+disposable Postgres databases, so it is the *test* database. Convex is where an
+app's data lives. They do share one thing: the cluster.
+
+- **Postgres in Ghost's cluster**, so the box runs one Postgres, not two.
+  Upstream's default is SQLite. Convex gets its own database
+  (`convex_self_hosted`), owned by its own role (`convex`), with `CONNECT`
+  revoked from `PUBLIC`. `tsdbadmin`, the shared role Ghost gives to agents,
+  cannot open it ("User does not have CONNECT privilege"), and
+  `ghost password` does not touch it. `ghost-server` only acts on databases
+  listed in its own `ghost.databases` table. Sizes, forks, pauses, deletes and
+  connection kills all join on that table. So `ghost list` never shows
+  Convex's database, and nothing Ghost does can drop it. The storage limit is
+  reported, not enforced (`internal/server/config.go` in the fork).
+- **One network, owned by Ghost.** `ghost-postgres` and `convex-backend` both
+  join `venari-postgres`. Ghost's compose file creates it; Convex's declares
+  it external. So Ghost runs with or without Convex, and Convex needs Ghost
+  up first, which it needs for the database anyway. `docker compose down` in
+  `/srv/ghost` while Convex is attached keeps the network ("Resource is still
+  in use", exit 0); Convex keeps its route, and the next `up` reattaches
+  Postgres (checked with Docker Compose 2 on 2026-10-16).
+- **Plaintext on that network.** The backend verifies Postgres TLS, and
+  Ghost's certificate is self-signed, so a handshake fails with
+  `CaUsedAsEndEntity`. The fix needs both `DO_NOT_REQUIRE_SSL=1` and
+  `?sslmode=disable`; either one alone still fails. The hop is container to
+  container and never leaves the host. The alternative, not tested, is to
+  re-issue Ghost's certificate from a CA the backend trusts.
+- **A connection budget.** The cluster allows 25 connections, 3 reserved for
+  superusers (TimescaleDB derives the limit from its memory). Convex's pool is
+  capped at 8 (`POSTGRES_MAX_CONNECTIONS`; its default of 128 could take every
+  slot), and the `convex` role has `CONNECTION LIMIT 10`, so Postgres enforces
+  the cap whatever the knob says. That leaves about 12 for agents' Ghost
+  databases. Under a 500-mutation burst Convex used 7.
+- **State is split across two places.** The documents are in
+  `convex_self_hosted` in the cluster. Files, function modules, search indexes
+  (`data/storage/`) and `data/credentials/` (the instance name, and the secret
+  that admin keys are signed with) are on disk. A backup needs both from the
+  same moment. Two kinds of copy give that: a whole-disk snapshot of the box,
+  which takes both at once (crash-consistent, like a power cut, *if* the
+  provider snapshots the disk atomically, which nobody has checked), and
+  `npx convex export`, which is consistent by construction and is the only
+  copy that leaves the box. Copying the two halves separately (a `pg_dump`
+  of the database, then `data/`) does not.
+
+Measured on 2026-09-22 in a sandbox, not on venari. The setup there followed
+this README: Ghost with its self-signed certificate, and Convex on the same
+cluster, both at the pinned images.
+
+- **A workload.** A project with a schema, a mutation, a query and a
+  `"use node"` action deployed with `npx convex deploy` (convex 1.46.0). A
+  `ConvexClient` subscription saw 271 pushed updates, from 1 row to 501, while
+  500 concurrent mutations ran.
+- **Ghost unaffected.** `ghost create`, `fork`, `delete` and `list` behaved
+  as before.
+- **Outages.** With `/srv/ghost` brought `down` and back up, Convex never
+  restarted and kept its data. On a cold start with Convex first, it
+  crash-looped (7 restarts) until the cluster was healthy, then recovered by
+  itself. `restart: unless-stopped` is what gets it through a reboot, because
+  `depends_on` cannot reach across compose projects.
+- **Peak memory.** Convex backend 132 MiB and dashboard 88 MiB, against limits
+  of 512m and 384m. `ghost-postgres` peaked at 213 MiB of its 768m while
+  serving both. Across all containers, the box's limits total about 2 GB of
+  its 4 GB.
+- **Disk.** The images take about 1.5 GB (798 MB + 668 MB).
+
+None of these are load figures for this box, which has 2 vCPUs.
+
+All three ports listen on the box's loopback (3210 API, 3211 HTTP actions,
+6791 dashboard). The tunnel's laptop ends are the same numbers plus 10000,
+like Ghost's 15432, because 3210/3211 are where a local `npx convex dev`
+deployment starts. With equal numbers, a project whose `.env.local` says
+`127.0.0.1:3210` would deploy to whichever backend held the port. From the
+laptop:
+
+```sh
+just convex-tunnel                      # 13210 -> API, 13211 -> HTTP actions, 16791 -> dashboard
+just convex-admin-key                   # prints a new admin key (via venari-root)
+open http://127.0.0.1:16791             # dashboard; paste the admin key
+just convex-tunnel-close
+```
+
+In a Convex project, put the URL and key in `.env.local`, which is gitignored
+by the project and never in this repo. `npx convex dev` and `deploy` then
+target venari:
+
+```sh
+CONVEX_SELF_HOSTED_URL='http://127.0.0.1:13210'
+CONVEX_SELF_HOSTED_ADMIN_KEY='<from just convex-admin-key>'
+```
+
+Every call to `generate_admin_key.sh` returns a different key. All of them
+stay valid, because they are signed with the instance secret in `data/`. A
+key issued before a restart still worked after it. So there is no single key
+to keep in agenix. Revoking a key means rotating the instance secret, which
+invalidates every key.
+
+`CONVEX_CLOUD_ORIGIN` and `NEXT_PUBLIC_DEPLOYMENT_URL` say
+`http://127.0.0.1:13210`, which is the laptop's end of the tunnel. That means
+this deployment serves one person through ssh. A frontend that other people
+use needs a public HTTPS origin for the API. That means a port other than 22
+in the cloud firewall and a TLS reverse proxy. It is a separate decision,
+not a config change.
+
+Both outbound calls the images make by default are off. `DISABLE_BEACON`
+turns off the anonymous usage ping. `NEXT_PUBLIC_LOAD_MONACO_INTERNALLY`
+serves the dashboard's editor from the image instead of from a CDN.
+
+Setup, as root on the box, after copying `convex/` here to `/srv/convex/`.
+Ghost must be running from this repo's `ghost/docker-compose.yml`, which
+creates `venari-postgres`. A box still on the older Ghost file needs one
+`docker compose up` there first; it re-creates Postgres on the new network.
+
+```sh
+(cd /srv/ghost && docker compose up -d --wait)      # creates venari-postgres if missing
+
+cd /srv/convex && umask 077 && mkdir -p data
+printf 'CONVEX_POSTGRES_PASSWORD=%s\n' "$(openssl rand -hex 24)" > .env
+. ./.env
+(cd /srv/ghost && docker compose exec -T postgres psql -v ON_ERROR_STOP=1 -U postgres -v pw="$CONVEX_POSTGRES_PASSWORD") <<'SQL'
+CREATE ROLE convex LOGIN CONNECTION LIMIT 10 PASSWORD :'pw';
+CREATE DATABASE convex_self_hosted OWNER convex;
+REVOKE CONNECT, TEMPORARY ON DATABASE convex_self_hosted FROM PUBLIC;
+SQL
+docker compose up -d --wait
+docker compose logs backend | grep -m1 'Connected to Postgres'
+```
+
+Upgrading, from upstream `self-hosted/advanced/upgrading.md`:
+
+1. Run `npx convex export` from a project against this deployment, so there is
+   a copy to restore.
+2. Bump **both** image tags to the same revision. Upstream does not guarantee
+   that a mismatched backend and dashboard work together.
+3. Run `docker compose up -d --wait`, then watch the logs for the
+   `MigrationComplete` line.
 
 ## Updates and reboots
 
@@ -209,7 +356,15 @@ original: a `*.bak-<ts>` left in `/etc/apt/apt.conf.d/` makes apt print
 
 ## Not covered yet
 
-- Backups. `data/` (repos plus db) should be backed up as a unit, and the
+- Backups. Soft Serve's `data/` (repos plus db) should be backed up as a unit, and the
   planned home for that is restic to R2. `ledger-age` is itself a backup
   (ciphertext, with the plaintext still on felixia), so losing it is
   recoverable. The Moment repos are not.
+  Ghost's cluster is no longer all disposable: `convex_self_hosted` in it,
+  plus Convex's `data/`, is application data. On the box it rides the
+  provider's backups like everything else (see "Ghost"), which is one
+  copy, on the same provider, whose atomicity is unchecked. Until restic
+  lands, `npx convex export` from the laptop is the only off-box backup and
+  the only one consistent by construction. Restic for Convex must not
+  repeat the separate-copies mistake: export, or dump and copy with the
+  backend stopped.
diff --git a/tools/venari/convex/.env.example b/tools/venari/convex/.env.example
new file mode 100644
index 00000000..fbae1ea3
--- /dev/null
+++ b/tools/venari/convex/.env.example
@@ -0,0 +1,4 @@
+# Copy to .env on the box (mode 600). Generated there:
+#   CONVEX_POSTGRES_PASSWORD=$(openssl rand -hex 24)
+# The same value goes into the role in Ghost's cluster (README, "Convex").
+CONVEX_POSTGRES_PASSWORD=
diff --git a/tools/venari/convex/.gitignore b/tools/venari/convex/.gitignore
new file mode 100644
index 00000000..24f9f8d0
--- /dev/null
+++ b/tools/venari/convex/.gitignore
@@ -0,0 +1,2 @@
+.env
+data/
diff --git a/tools/venari/convex/docker-compose.yml b/tools/venari/convex/docker-compose.yml
new file mode 100644
index 00000000..b82ac04f
--- /dev/null
+++ b/tools/venari/convex/docker-compose.yml
@@ -0,0 +1,77 @@
+# Convex on venari: the self-hosted backend and dashboard, from
+# convex/convex-backend's self-hosted/docker/docker-compose.yml.
+#
+# On the box: /srv/convex/docker-compose.yml, next to an untracked .env (see
+# .env.example) and data/ (never tracked). The database is in Ghost's cluster,
+# so Ghost must be up first.
+#
+# The reasons for every choice below - the shared cluster and its isolation,
+# the network, plaintext, the connection budget, the port offset, the pinned
+# revision, admin keys and backups - are in tools/venari/README.md, "Convex",
+# and only there. The comments here say what must stay true when you edit.
+name: convex
+services:
+  backend:
+    # 0cf49cb = convex/convex-backend main on 2026-09-21; the tag :latest
+    # pointed at on 2026-09-22.
+    # ghcr.io/convex/, not get-convex/: the old path went away with the org
+    # rename (denied, even for :latest), though upstream's compose still names it.
+    image: ghcr.io/convex/convex-backend:0cf49cbf8c4b7e22e631ceda9b5111f6cccbcd49
+    container_name: convex-backend
+    restart: unless-stopped
+    stop_grace_period: 10s
+    stop_signal: SIGINT
+    volumes:
+      - ./data:/convex/data
+    networks:
+      - default
+      - venari-postgres
+    ports:
+      - "127.0.0.1:3210:3210" # client API, websocket sync
+      - "127.0.0.1:3211:3211" # HTTP actions
+    environment:
+      # The laptop's end of the tunnel, not the container's address. Must match
+      # the forwards in `just convex-tunnel` (box port + 10000).
+      CONVEX_CLOUD_ORIGIN: http://127.0.0.1:13210
+      CONVEX_SITE_ORIGIN: http://127.0.0.1:13211
+      # No database name: the backend appends one derived from INSTANCE_NAME
+      # (default convex-self-hosted -> convex_self_hosted). Plaintext on
+      # purpose; it takes BOTH sslmode=disable and DO_NOT_REQUIRE_SSL.
+      POSTGRES_URL: "postgresql://convex:${CONVEX_POSTGRES_PASSWORD:?set it in .env}@ghost-postgres:5432?sslmode=disable"
+      DO_NOT_REQUIRE_SSL: "1"
+      # Keep below the convex role's CONNECTION LIMIT (10, README setup). The
+      # cluster has 25 connections in total, shared with every Ghost database.
+      POSTGRES_MAX_CONNECTIONS: "8"
+      # The anonymous usage beacon (a random ID plus the backend version).
+      DISABLE_BEACON: "true"
+      DISABLE_METRICS_ENDPOINT: "true"
+      # Upstream's compose default: keep old document versions for 2 days.
+      DOCUMENT_RETENTION_DELAY: "172800"
+      RUST_LOG: info
+    healthcheck:
+      test: curl -f http://localhost:3210/version
+      interval: 5s
+      start_period: 10s
+    mem_limit: 512m
+
+  dashboard:
+    image: ghcr.io/convex/convex-dashboard:0cf49cbf8c4b7e22e631ceda9b5111f6cccbcd49
+    container_name: convex-dashboard
+    restart: unless-stopped
+    stop_grace_period: 10s
+    stop_signal: SIGINT
+    ports:
+      - "127.0.0.1:6791:6791"
+    environment:
+      # Read in the browser, so it is the laptop's tunnel end too.
+      NEXT_PUBLIC_DEPLOYMENT_URL: http://127.0.0.1:13210
+      # Otherwise the editor panes load monaco from a CDN.
+      NEXT_PUBLIC_LOAD_MONACO_INTERNALLY: "true"
+    depends_on:
+      backend:
+        condition: service_healthy
+    mem_limit: 384m
+
+networks:
+  venari-postgres:
+    external: true
diff --git a/tools/venari/ghost/docker-compose.yml b/tools/venari/ghost/docker-compose.yml
index 1284f260..3bdb006f 100644
--- a/tools/venari/ghost/docker-compose.yml
+++ b/tools/venari/ghost/docker-compose.yml
@@ -32,6 +32,14 @@ services:
       - ./certs:/certs:ro
     ports:
       - "127.0.0.1:5432:5432"
+    # Also on venari-postgres, the network Convex reaches this cluster through
+    # (tools/venari/convex/docker-compose.yml). This project creates it, so
+    # Ghost needs no setup step for Convex's sake. `docker compose down` here
+    # while Convex is attached leaves it in place ("Resource is still in use",
+    # exit 0) and Convex keeps running; the next `up` reattaches postgres.
+    networks:
+      - default
+      - venari-postgres
     shm_size: 128m
     mem_limit: 768m
     healthcheck:
@@ -62,3 +70,7 @@ services:
     ports:
       - "127.0.0.1:8787:8787"
     mem_limit: 128m
+
+networks:
+  venari-postgres:
+    name: venari-postgres # fixed, so Convex can name it; no project prefix