feat(journal): two-instance federation harness + trails↔trails Accept fix (§11)

The 11.4 harness — e2e/federation/: postgres (two DBs) + a Caddy with
an internal CA terminating real HTTPS between two complete journal
containers (journal-a.test / journal-b.test), driven by an opt-in
integration test (FEDERATION_TWO_INSTANCE=1, via run.sh). The driver
seeds users straight into each DB, mints a signed session cookie
(known SESSION_SECRET), follows across instances through the real
/follows/outgoing route, and asserts the full pipeline: Follow →
auto-Accept → settle → first outbox poll → bob's public activity
rendered in alice's /feed with @bob@journal-b.test attribution. Plus a
wire-level 11.3 check: unsigned Create(Note) → 4xx, no DB writes.

And the harness immediately earned its keep — it caught a real
trails↔trails bug Mastodon interop never could: our Follow ids are
fragment URIs on OUR domain, so the Follow embedded in another trails
instance's Accept is cross-origin and Fedify rightly distrusts it;
re-fetching the id returns the actor document, getObject() yields a
Person, and the Accept/Reject/Undo listeners bailed silently — follows
stayed Pending forever. The listeners now fall back to the wire
objectId (captured BEFORE getObject(), which memoizes the fetched
document and changes what objectId reports) validated against our
Follow-id shape + the personal inbox's ctx.recipient. Forgery-safe:
settleOutgoingFollow only matches a Pending row toward the
HTTP-Signature-authenticated sender.

Supporting changes:
- federation.server.ts: env-gated allowPrivateAddress
  (FEDERATION_ALLOW_PRIVATE_ADDRESS=true) so the harness's RFC 1918
  Docker network is fetchable — testing only, loudly documented.
- Root .dockerignore: local builds shipped a 1GB+ context and
  overlaid host (darwin) node_modules over the image's own install
  via COPY . . — CI never noticed because it builds from clean
  checkouts. Context is now ~5MB.
- tasks.md: 11.1–11.7 marked with provenance notes; design.md gains
  the cross-origin embedded-object lesson.

Gate: typecheck ✓ lint ✓ unit+integration (FEDERATION_INTEGRATION=1) ✓
e2e 71/72 + known komoot flake green isolated ✓ harness run clean from
scratch (2/2, teardown included) ✓

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

e2e/federation/Caddyfile

@@ -0,0 +1,16 @@
+# TLS terminator for the two-instance federation harness. `local_certs`
+# issues every site cert from Caddy's internal CA; the journals trust it
+# via NODE_EXTRA_CA_CERTS (see docker-compose.yml).
+{
+	local_certs
+	# No public reachability — don't try (or wait on) ACME/OCSP anything.
+	skip_install_trust
+}
+
+journal-a.test {
+	reverse_proxy journal-a:3000
+}
+
+journal-b.test {
+	reverse_proxy journal-b:3000
+}

e2e/federation/README.md

@@ -0,0 +1,56 @@
+# Two-instance federation harness
+
+Spec: `openspec/changes/social-federation/` task 11.4.
+
+Two complete journal instances — `journal-a.test` and `journal-b.test` —
+federate with each other inside a Docker network, with real HTTPS
+between them (a Caddy with `local_certs` terminates TLS; the journals
+trust its internal CA via `NODE_EXTRA_CA_CERTS`). The driver test seeds
+a user on each side, follows across instances through the real UI
+route, and asserts the full pipeline:
+
+```
+alice@journal-a  ──Follow──▶  bob@journal-b   (NodeInfo + WebFinger +
+                ◀──Accept──                    actor fetch over TLS)
+                ──signed outbox poll──▶
+alice's /feed shows bob's public activity with @bob@journal-b.test
+```
+
+## Run it
+
+```bash
+./e2e/federation/run.sh              # build, test, tear down
+KEEP_STACK=1 ./e2e/federation/run.sh # leave the stack up afterwards
+```
+
+First run builds the journal image (a few minutes); later runs reuse it.
+Opt-in only — nothing here runs under `pnpm test`, `pnpm test:e2e`, or
+CI. The driver lives at
+`apps/journal/app/lib/federation-two-instance.integration.test.ts`
+(gated by `FEDERATION_TWO_INSTANCE=1`).
+
+## How the driver authenticates
+
+Sessions are signed cookies (`auth/session.server.ts`). The harness
+journals run with a known `SESSION_SECRET`, so the driver mints a valid
+`__session` cookie for the seeded user instead of driving the WebAuthn
+ceremony. That secret (and everything else in the compose env) is a
+throwaway test value on a loopback-only stack.
+
+## Why `FEDERATION_ALLOW_PRIVATE_ADDRESS`
+
+Fedify's document loader refuses private network addresses (SSRF
+guard). Both instances here live on RFC 1918 Docker addresses, so the
+harness sets `FEDERATION_ALLOW_PRIVATE_ADDRESS=true` — the env-gated
+opt-out in `federation.server.ts`. Never set it in a real deployment.
+
+## Debugging
+
+```bash
+docker compose -f e2e/federation/docker-compose.yml logs -f journal-a
+docker compose -f e2e/federation/docker-compose.yml exec postgres \
+  psql -U trails trails_a -c 'TABLE journal.follows'
+```
+
+`FEDERATION_LOG_LEVEL=debug` is already on — Fedify logs every
+signature verification and delivery attempt.

e2e/federation/docker-compose.yml

@@ -0,0 +1,145 @@
+# Two-instance federation harness (social-federation task 11.4).
+#
+# Brings up two complete journal instances — journal-a.test and
+# journal-b.test — that federate with each other over a private Docker
+# network, with real HTTPS between them (Caddy internal CA; the journals
+# trust it via NODE_EXTRA_CA_CERTS). Driven by
+# apps/journal/app/lib/federation-two-instance.integration.test.ts via
+# ./run.sh — see README.md.
+#
+# Ports published to the host (driver-facing, loopback only):
+#   127.0.0.1:5499 → postgres        (schema push + seeding + asserts)
+#   127.0.0.1:3401 → journal-a :3000 (plain HTTP; the TLS hop is only
+#   127.0.0.1:3402 → journal-b :3000  needed for instance↔instance)
+
+name: trails-federation-e2e
+# Shared journal environment. Secrets here are throwaway test values —
+# the whole stack is loopback-only and torn down by run.sh.
+x-journal-env: &journal-env
+  SESSION_SECRET: two-instance-test-secret
+  FEDERATION_ENABLED: "true"
+  FEDERATION_KEY_ENCRYPTION_KEY: two-instance-test-encryption-key
+  FEDERATION_LOG_LEVEL: debug
+  LOG_LEVEL: debug
+  # Both instances live on RFC 1918 Docker addresses; Fedify's SSRF
+  # guard must be told to stand down. Testing only — see the comment in
+  # apps/journal/app/lib/federation.server.ts.
+  FEDERATION_ALLOW_PRIVATE_ADDRESS: "true"
+  # Trust Caddy's internal CA for the instance↔instance HTTPS hop.
+  # Published world-readable by the ca-publisher one-shot — the journal
+  # runs as a non-root user and can't read caddy's 0700 data volume.
+  NODE_EXTRA_CA_CERTS: /ca/root.crt
+  SENTRY_DISABLED: "true"
+
+
+services:
+  postgres:
+    image: imresamu/postgis:16-3.4 # multi-arch, same as docker-compose.dev.yml
+    environment:
+      POSTGRES_USER: trails
+      POSTGRES_PASSWORD: trails
+      POSTGRES_DB: trails_a
+    volumes:
+      - ./init-dbs.sql:/docker-entrypoint-initdb.d/90-init-dbs.sql:ro
+    ports:
+      - "127.0.0.1:5499:5432"
+    healthcheck:
+      # -h 127.0.0.1 forces TCP: during first-boot initdb a temporary
+      # postgres answers on the unix socket only, and a socket-based
+      # pg_isready reports healthy before the init scripts have run.
+      test: ["CMD-SHELL", "pg_isready -h 127.0.0.1 -U trails -d trails_b"]
+      interval: 2s
+      timeout: 3s
+      retries: 30
+
+  caddy:
+    image: caddy:2-alpine
+    volumes:
+      - ./Caddyfile:/etc/caddy/Caddyfile:ro
+      - caddy-data:/data
+    networks:
+      default:
+        # The instances reach each other through Caddy: these aliases
+        # make journal-a.test / journal-b.test resolve to the proxy
+        # inside the compose network.
+        aliases:
+          - journal-a.test
+          - journal-b.test
+    healthcheck:
+      # The journals read the internal CA root at process start
+      # (NODE_EXTRA_CA_CERTS) — gate their startup on it existing.
+      test: ["CMD", "test", "-f", "/data/caddy/pki/authorities/local/root.crt"]
+      interval: 2s
+      timeout: 3s
+      retries: 30
+
+  # One-shot: copies Caddy's internal root CA into a volume the
+  # non-root journal user can actually read (caddy's own data dir is
+  # 0700 root).
+  ca-publisher:
+    image: caddy:2-alpine
+    entrypoint:
+      - sh
+      - -c
+      - |
+        until [ -f /data/caddy/pki/authorities/local/root.crt ]; do sleep 0.5; done
+        cp /data/caddy/pki/authorities/local/root.crt /ca/root.crt
+        chmod 444 /ca/root.crt
+    volumes:
+      - caddy-data:/data:ro
+      - ca-cert:/ca
+    depends_on:
+      caddy:
+        condition: service_healthy
+
+  journal-a:
+    build:
+      context: ../..
+      dockerfile: apps/journal/Dockerfile
+    image: trails-federation-e2e-journal
+    pull_policy: never
+    environment:
+      <<: *journal-env
+      DATABASE_URL: postgres://trails:trails@postgres:5432/trails_a
+      ORIGIN: https://journal-a.test
+    ports:
+      - "127.0.0.1:3401:3000"
+    volumes:
+      - ca-cert:/ca:ro
+    healthcheck: &journal-health
+      test: ["CMD", "curl", "-fsS", "http://localhost:3000/api/health"]
+      interval: 3s
+      timeout: 5s
+      retries: 40
+      start_period: 10s
+    depends_on:
+      postgres:
+        condition: service_healthy
+      ca-publisher:
+        condition: service_completed_successfully
+
+  journal-b:
+    # Image-only on purpose: run.sh builds it once via journal-a before
+    # `up`. Building from both services races the export of the shared
+    # tag ("already exists"), and a registry pull must never happen.
+    image: trails-federation-e2e-journal
+    pull_policy: never
+    environment:
+      <<: *journal-env
+      DATABASE_URL: postgres://trails:trails@postgres:5432/trails_b
+      ORIGIN: https://journal-b.test
+    ports:
+      - "127.0.0.1:3402:3000"
+    volumes:
+      - ca-cert:/ca:ro
+    healthcheck: *journal-health
+    depends_on:
+      postgres:
+        condition: service_healthy
+      ca-publisher:
+        condition: service_completed_successfully
+
+volumes:
+  caddy-data:
+  ca-cert:
+

e2e/federation/init-dbs.sql

@@ -0,0 +1,6 @@
+-- Second instance database. trails_a is the image's POSTGRES_DB (the
+-- postgis image creates the extension there itself); trails_b needs
+-- both created by hand. Runs once on first postgres boot.
+CREATE DATABASE trails_b;
+\connect trails_b
+CREATE EXTENSION IF NOT EXISTS postgis;

e2e/federation/run.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# Two-instance federation harness runner (social-federation 11.4).
+#
+#   ./e2e/federation/run.sh            # build, test, tear down
+#   KEEP_STACK=1 ./e2e/federation/run.sh   # leave the stack up for poking
+#
+# Brings up two journal instances that federate with each other (see
+# docker-compose.yml), pushes the Drizzle schema into both databases,
+# and runs the driver test. Opt-in and self-contained — nothing here is
+# wired into `pnpm test` or CI.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+compose() { docker compose -f "$SCRIPT_DIR/docker-compose.yml" "$@"; }
+
+cleanup() {
+  if [[ "${KEEP_STACK:-}" == "1" ]]; then
+    echo "KEEP_STACK=1 — leaving the stack up. Tear down with:"
+    echo "  docker compose -f $SCRIPT_DIR/docker-compose.yml down -v"
+  else
+    compose down -v --remove-orphans >/dev/null 2>&1 || true
+  fi
+}
+trap cleanup EXIT
+
+echo "==> postgres + caddy (internal CA)"
+compose up -d --wait postgres caddy
+
+echo "==> pushing schema into trails_a and trails_b"
+push_schema() {
+  # A transient postgres backend crash mid-introspection has been seen
+  # under Docker Desktop load ("Connection terminated unexpectedly" +
+  # crash recovery). Retry after the healthcheck reports the server
+  # recovered — without hiding a deterministic failure.
+  local url="$1" attempt
+  for attempt in 1 2 3; do
+    if DATABASE_URL="$url" pnpm --dir "$ROOT" db:push; then return 0; fi
+    echo "schema push failed (attempt $attempt) — waiting for postgres to recover"
+    sleep 5
+    compose up -d --wait postgres
+  done
+  return 1
+}
+push_schema postgres://trails:trails@127.0.0.1:5499/trails_a
+push_schema postgres://trails:trails@127.0.0.1:5499/trails_b
+
+echo "==> building the journal image (slow on first run)"
+compose build journal-a
+
+echo "==> journal-a + journal-b"
+compose up -d --wait journal-a journal-b
+
+echo "==> driving the federation flow"
+FEDERATION_TWO_INSTANCE=1 pnpm --dir "$ROOT/apps/journal" exec vitest run app/lib/federation-two-instance.integration.test.ts