diff --git a/bin/disinto b/bin/disinto
index bf8edc4..18179df 100755
--- a/bin/disinto
+++ b/bin/disinto
@@ -1488,15 +1488,28 @@ p.write_text(text)
     touch "${FACTORY_ROOT}/.env"
   fi
 
-  # Configure Forgejo and Woodpecker subpath URLs when EDGE_TUNNEL_FQDN is set
+  # Configure Forgejo and Woodpecker URLs when EDGE_TUNNEL_FQDN is set.
+  # In subdomain mode, uses per-service FQDNs at root path instead of subpath URLs.
   if [ -n "${EDGE_TUNNEL_FQDN:-}" ]; then
-    # Forgejo ROOT_URL with /forge/ subpath (note trailing slash - Forgejo needs it)
-    if ! grep -q '^FORGEJO_ROOT_URL=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
-      echo "FORGEJO_ROOT_URL=https://${EDGE_TUNNEL_FQDN}/forge/" >> "${FACTORY_ROOT}/.env"
-    fi
-    # Woodpecker WOODPECKER_HOST with /ci subpath (no trailing slash for v3)
-    if ! grep -q '^WOODPECKER_HOST=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
-      echo "WOODPECKER_HOST=https://${EDGE_TUNNEL_FQDN}/ci" >> "${FACTORY_ROOT}/.env"
+    local routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+    if [ "$routing_mode" = "subdomain" ]; then
+      # Subdomain mode: Forgejo at forge.<project>.disinto.ai (root path)
+      if ! grep -q '^FORGEJO_ROOT_URL=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
+        echo "FORGEJO_ROOT_URL=https://${EDGE_TUNNEL_FQDN_FORGE:-forge.${EDGE_TUNNEL_FQDN}}/" >> "${FACTORY_ROOT}/.env"
+      fi
+      # Subdomain mode: Woodpecker at ci.<project>.disinto.ai (root path)
+      if ! grep -q '^WOODPECKER_HOST=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
+        echo "WOODPECKER_HOST=https://${EDGE_TUNNEL_FQDN_CI:-ci.${EDGE_TUNNEL_FQDN}}" >> "${FACTORY_ROOT}/.env"
+      fi
+    else
+      # Subpath mode: Forgejo ROOT_URL with /forge/ subpath (trailing slash required)
+      if ! grep -q '^FORGEJO_ROOT_URL=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
+        echo "FORGEJO_ROOT_URL=https://${EDGE_TUNNEL_FQDN}/forge/" >> "${FACTORY_ROOT}/.env"
+      fi
+      # Subpath mode: Woodpecker WOODPECKER_HOST with /ci subpath (no trailing slash for v3)
+      if ! grep -q '^WOODPECKER_HOST=' "${FACTORY_ROOT}/.env" 2>/dev/null; then
+        echo "WOODPECKER_HOST=https://${EDGE_TUNNEL_FQDN}/ci" >> "${FACTORY_ROOT}/.env"
+      fi
     fi
   fi
 
@@ -1603,9 +1616,15 @@ p.write_text(text)
   create_woodpecker_oauth "$forge_url" "$forge_repo"
 
   # Create OAuth2 app on Forgejo for disinto-chat (#708)
+  # In subdomain mode, callback is at chat.<project> root instead of /chat/ subpath.
   local chat_redirect_uri
   if [ -n "${EDGE_TUNNEL_FQDN:-}" ]; then
-    chat_redirect_uri="https://${EDGE_TUNNEL_FQDN}/chat/oauth/callback"
+    local chat_routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+    if [ "$chat_routing_mode" = "subdomain" ]; then
+      chat_redirect_uri="https://${EDGE_TUNNEL_FQDN_CHAT:-chat.${EDGE_TUNNEL_FQDN}}/oauth/callback"
+    else
+      chat_redirect_uri="https://${EDGE_TUNNEL_FQDN}/chat/oauth/callback"
+    fi
   else
     chat_redirect_uri="http://localhost/chat/oauth/callback"
   fi
@@ -2805,15 +2824,29 @@ disinto_edge() {
       # Write to .env (replace existing entries to avoid duplicates)
       local tmp_env
       tmp_env=$(mktemp)
-      grep -Ev "^EDGE_TUNNEL_(HOST|PORT|FQDN)=" "$env_file" > "$tmp_env" 2>/dev/null || true
+      grep -Ev "^EDGE_TUNNEL_(HOST|PORT|FQDN|FQDN_FORGE|FQDN_CI|FQDN_CHAT)=" "$env_file" > "$tmp_env" 2>/dev/null || true
       mv "$tmp_env" "$env_file"
       echo "EDGE_TUNNEL_HOST=${edge_host}" >> "$env_file"
       echo "EDGE_TUNNEL_PORT=${port}" >> "$env_file"
       echo "EDGE_TUNNEL_FQDN=${fqdn}" >> "$env_file"
 
+      # Subdomain mode: write per-service FQDNs (#1028)
+      local reg_routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+      if [ "$reg_routing_mode" = "subdomain" ]; then
+        echo "EDGE_TUNNEL_FQDN_FORGE=forge.${fqdn}" >> "$env_file"
+        echo "EDGE_TUNNEL_FQDN_CI=ci.${fqdn}" >> "$env_file"
+        echo "EDGE_TUNNEL_FQDN_CHAT=chat.${fqdn}" >> "$env_file"
+      fi
+
       echo "Registered: ${project}"
       echo "  Port:    ${port}"
       echo "  FQDN:    ${fqdn}"
+      if [ "$reg_routing_mode" = "subdomain" ]; then
+        echo "  Mode:    subdomain"
+        echo "  Forge:   forge.${fqdn}"
+        echo "  CI:      ci.${fqdn}"
+        echo "  Chat:    chat.${fqdn}"
+      fi
       echo "  Saved to: ${env_file}"
       ;;
 
diff --git a/docker/chat/server.py b/docker/chat/server.py
index 6748354..ef37fb1 100644
--- a/docker/chat/server.py
+++ b/docker/chat/server.py
@@ -45,6 +45,8 @@ FORGE_URL = os.environ.get("FORGE_URL", "http://localhost:3000")
 CHAT_OAUTH_CLIENT_ID = os.environ.get("CHAT_OAUTH_CLIENT_ID", "")
 CHAT_OAUTH_CLIENT_SECRET = os.environ.get("CHAT_OAUTH_CLIENT_SECRET", "")
 EDGE_TUNNEL_FQDN = os.environ.get("EDGE_TUNNEL_FQDN", "")
+EDGE_TUNNEL_FQDN_CHAT = os.environ.get("EDGE_TUNNEL_FQDN_CHAT", "")
+EDGE_ROUTING_MODE = os.environ.get("EDGE_ROUTING_MODE", "subpath")
 
 # Shared secret for Caddy forward_auth verify endpoint (#709).
 # When set, only requests carrying this value in X-Forward-Auth-Secret are
@@ -102,6 +104,8 @@ MIME_TYPES = {
 
 def _build_callback_uri():
     """Build the OAuth callback URI based on tunnel configuration."""
+    if EDGE_ROUTING_MODE == "subdomain" and EDGE_TUNNEL_FQDN_CHAT:
+        return f"https://{EDGE_TUNNEL_FQDN_CHAT}/oauth/callback"
     if EDGE_TUNNEL_FQDN:
         return f"https://{EDGE_TUNNEL_FQDN}/chat/oauth/callback"
     return "http://localhost/chat/oauth/callback"
diff --git a/lib/ci-setup.sh b/lib/ci-setup.sh
index 319e83e..507affb 100644
--- a/lib/ci-setup.sh
+++ b/lib/ci-setup.sh
@@ -142,6 +142,7 @@ _create_forgejo_oauth_app() {
 
 # Set up Woodpecker CI to use Forgejo as its forge backend.
 # Creates an OAuth2 app on Forgejo for Woodpecker, activates the repo.
+# Respects EDGE_ROUTING_MODE: in subdomain mode, uses EDGE_TUNNEL_FQDN_CI for redirect URI.
 # Usage: create_woodpecker_oauth <forge_url> <repo_slug>
 _create_woodpecker_oauth_impl() {
   local forge_url="$1"
@@ -150,7 +151,13 @@ _create_woodpecker_oauth_impl() {
   echo ""
   echo "── Woodpecker OAuth2 setup ────────────────────────────"
 
-  _create_forgejo_oauth_app "woodpecker-ci" "http://localhost:8000/authorize" || return 0
+  local wp_redirect_uri="http://localhost:8000/authorize"
+  local routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+  if [ "$routing_mode" = "subdomain" ] && [ -n "${EDGE_TUNNEL_FQDN_CI:-}" ]; then
+    wp_redirect_uri="https://${EDGE_TUNNEL_FQDN_CI}/authorize"
+  fi
+
+  _create_forgejo_oauth_app "woodpecker-ci" "$wp_redirect_uri" || return 0
   local client_id="${_OAUTH_CLIENT_ID}"
   local client_secret="${_OAUTH_CLIENT_SECRET}"
 
@@ -158,10 +165,15 @@ _create_woodpecker_oauth_impl() {
   # WP_FORGEJO_CLIENT/SECRET match the docker-compose.yml variable references
   # WOODPECKER_HOST must be host-accessible URL to match OAuth2 redirect_uri
   local env_file="${FACTORY_ROOT}/.env"
+  local wp_host="http://localhost:8000"
+  if [ "$routing_mode" = "subdomain" ] && [ -n "${EDGE_TUNNEL_FQDN_CI:-}" ]; then
+    wp_host="https://${EDGE_TUNNEL_FQDN_CI}"
+  fi
+
   local wp_vars=(
     "WOODPECKER_FORGEJO=true"
     "WOODPECKER_FORGEJO_URL=${forge_url}"
-    "WOODPECKER_HOST=http://localhost:8000"
+    "WOODPECKER_HOST=${wp_host}"
   )
   if [ -n "${client_id:-}" ]; then
     wp_vars+=("WP_FORGEJO_CLIENT=${client_id}")
diff --git a/lib/generators.sh b/lib/generators.sh
index eb223e8..739ca50 100644
--- a/lib/generators.sh
+++ b/lib/generators.sh
@@ -607,9 +607,12 @@ COMPOSEEOF
       - EDGE_TUNNEL_USER=${EDGE_TUNNEL_USER:-tunnel}
       - EDGE_TUNNEL_PORT=${EDGE_TUNNEL_PORT:-}
       - EDGE_TUNNEL_FQDN=${EDGE_TUNNEL_FQDN:-}
-      # Subdomain fallback (#713): if subpath routing (#704/#708) fails, add:
-      #   EDGE_TUNNEL_FQDN_FORGE, EDGE_TUNNEL_FQDN_CI, EDGE_TUNNEL_FQDN_CHAT
-      # See docs/edge-routing-fallback.md for the full pivot plan.
+      # Subdomain fallback (#1028): per-service FQDNs for subdomain routing mode.
+      # Set EDGE_ROUTING_MODE=subdomain to activate. See docs/edge-routing-fallback.md.
+      - EDGE_ROUTING_MODE=${EDGE_ROUTING_MODE:-subpath}
+      - EDGE_TUNNEL_FQDN_FORGE=${EDGE_TUNNEL_FQDN_FORGE:-}
+      - EDGE_TUNNEL_FQDN_CI=${EDGE_TUNNEL_FQDN_CI:-}
+      - EDGE_TUNNEL_FQDN_CHAT=${EDGE_TUNNEL_FQDN_CHAT:-}
       # Shared secret for Caddy ↔ chat forward_auth (#709)
       - FORWARD_AUTH_SECRET=${FORWARD_AUTH_SECRET:-}
     volumes:
@@ -700,6 +703,8 @@ COMPOSEEOF
       CHAT_OAUTH_CLIENT_ID: ${CHAT_OAUTH_CLIENT_ID:-}
       CHAT_OAUTH_CLIENT_SECRET: ${CHAT_OAUTH_CLIENT_SECRET:-}
       EDGE_TUNNEL_FQDN: ${EDGE_TUNNEL_FQDN:-}
+      EDGE_TUNNEL_FQDN_CHAT: ${EDGE_TUNNEL_FQDN_CHAT:-}
+      EDGE_ROUTING_MODE: ${EDGE_ROUTING_MODE:-subpath}
       DISINTO_CHAT_ALLOWED_USERS: ${DISINTO_CHAT_ALLOWED_USERS:-}
       # Shared secret for Caddy forward_auth verify endpoint (#709)
       FORWARD_AUTH_SECRET: ${FORWARD_AUTH_SECRET:-}
@@ -805,6 +810,11 @@ _generate_agent_docker_impl() {
 # Output path: ${FACTORY_ROOT}/docker/Caddyfile (gitignored — generated artifact).
 # The edge compose service mounts this path as /etc/caddy/Caddyfile.
 # On a fresh clone, `disinto init` calls generate_caddyfile before first `disinto up`.
+#
+# Routing mode (EDGE_ROUTING_MODE env var):
+#   subpath   — (default) all services under <project>.disinto.ai/{forge,ci,chat,staging}
+#   subdomain — per-service subdomains: forge.<project>, ci.<project>, chat.<project>
+# See docs/edge-routing-fallback.md for the full pivot plan.
 _generate_caddyfile_impl() {
   local docker_dir="${FACTORY_ROOT}/docker"
   local caddyfile="${docker_dir}/Caddyfile"
@@ -814,8 +824,22 @@ _generate_caddyfile_impl() {
     return
   fi
 
+  local routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+
+  if [ "$routing_mode" = "subdomain" ]; then
+    _generate_caddyfile_subdomain "$caddyfile"
+  else
+    _generate_caddyfile_subpath "$caddyfile"
+  fi
+
+  echo "Created: ${caddyfile} (routing_mode=${routing_mode})"
+}
+
+# Subpath Caddyfile: all services under a single :80 block with path-based routing.
+_generate_caddyfile_subpath() {
+  local caddyfile="$1"
   cat > "$caddyfile" <<'CADDYFILEEOF'
-# Caddyfile — edge proxy configuration
+# Caddyfile — edge proxy configuration (subpath mode)
 # IP-only binding at bootstrap; domain + TLS added later via vault resource request
 
 :80 {
@@ -858,8 +882,50 @@ _generate_caddyfile_impl() {
     }
 }
 CADDYFILEEOF
+}
 
-  echo "Created: ${caddyfile}"
+# Subdomain Caddyfile: four host blocks per docs/edge-routing-fallback.md.
+# Uses env vars EDGE_TUNNEL_FQDN_FORGE, EDGE_TUNNEL_FQDN_CI, EDGE_TUNNEL_FQDN_CHAT,
+# and EDGE_TUNNEL_FQDN (main project domain → staging).
+_generate_caddyfile_subdomain() {
+  local caddyfile="$1"
+  cat > "$caddyfile" <<'CADDYFILEEOF'
+# Caddyfile — edge proxy configuration (subdomain mode)
+# Per-service subdomains; see docs/edge-routing-fallback.md
+
+# Main project domain — staging / landing
+{$EDGE_TUNNEL_FQDN} {
+    reverse_proxy staging:80
+}
+
+# Forgejo — root path, no subpath rewrite needed
+{$EDGE_TUNNEL_FQDN_FORGE} {
+    reverse_proxy forgejo:3000
+}
+
+# Woodpecker CI — root path
+{$EDGE_TUNNEL_FQDN_CI} {
+    reverse_proxy woodpecker:8000
+}
+
+# Chat — with forward_auth (#709, on its own host)
+{$EDGE_TUNNEL_FQDN_CHAT} {
+    handle /login {
+        reverse_proxy chat:8080
+    }
+    handle /oauth/callback {
+        reverse_proxy chat:8080
+    }
+    handle /* {
+        forward_auth chat:8080 {
+            uri /auth/verify
+            copy_headers X-Forwarded-User
+            header_up X-Forward-Auth-Secret {$FORWARD_AUTH_SECRET}
+        }
+        reverse_proxy chat:8080
+    }
+}
+CADDYFILEEOF
 }
 
 # Generate docker/index.html default page.
diff --git a/projects/disinto.toml.example b/projects/disinto.toml.example
index ebe6eed..34eacae 100644
--- a/projects/disinto.toml.example
+++ b/projects/disinto.toml.example
@@ -59,6 +59,23 @@ check_pipeline_stall = false
 #   compact_pct = 60
 #   poll_interval = 60
 
+# Edge routing mode (default: subpath)
+#
+# Controls how services are exposed through the edge proxy.
+#   subpath   — all services under <project>.disinto.ai/{forge,ci,chat,staging}
+#   subdomain — per-service subdomains: forge.<project>, ci.<project>, chat.<project>
+#
+# Set to "subdomain" if subpath routing causes unfixable issues (redirect loops,
+# OAuth callback mismatches, cookie collisions). See docs/edge-routing-fallback.md.
+#
+# Set in .env (not TOML) since it's consumed by docker-compose and shell scripts:
+#   EDGE_ROUTING_MODE=subdomain
+#
+# In subdomain mode, `disinto edge register` also writes:
+#   EDGE_TUNNEL_FQDN_FORGE=forge.<project>.disinto.ai
+#   EDGE_TUNNEL_FQDN_CI=ci.<project>.disinto.ai
+#   EDGE_TUNNEL_FQDN_CHAT=chat.<project>.disinto.ai
+
 # [mirrors]
 # github   = "git@github.com:johba/disinto.git"
 # codeberg = "git@codeberg.org:johba/disinto.git"
diff --git a/tools/edge-control/register.sh b/tools/edge-control/register.sh
index 3ac0d09..ee12ef7 100755
--- a/tools/edge-control/register.sh
+++ b/tools/edge-control/register.sh
@@ -39,13 +39,10 @@ EOF
   exit 1
 }
 
-# TODO(#713): Subdomain fallback — if subpath routing (#704/#708) fails, this
-# function would need to register additional routes for forge.<project>,
-# ci.<project>, chat.<project> subdomains (or accept a --subdomain parameter).
-# See docs/edge-routing-fallback.md for the full pivot plan.
-
 # Register a new tunnel
 # Usage: do_register <project> <pubkey>
+# When EDGE_ROUTING_MODE=subdomain, also registers forge.<project>, ci.<project>,
+# and chat.<project> subdomain routes (see docs/edge-routing-fallback.md).
 do_register() {
   local project="$1"
   local pubkey="$2"
@@ -79,17 +76,32 @@ do_register() {
   local port
   port=$(allocate_port "$project" "$full_pubkey" "${project}.${DOMAIN_SUFFIX}")
 
-  # Add Caddy route
+  # Add Caddy route for main project domain
   add_route "$project" "$port"
 
+  # Subdomain mode: register additional routes for per-service subdomains
+  local routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+  if [ "$routing_mode" = "subdomain" ]; then
+    local subdomain
+    for subdomain in forge ci chat; do
+      add_route "${subdomain}.${project}" "$port"
+    done
+  fi
+
   # Rebuild authorized_keys for tunnel user
   rebuild_authorized_keys
 
   # Reload Caddy
   reload_caddy
 
-  # Return JSON response
-  echo "{\"port\":${port},\"fqdn\":\"${project}.${DOMAIN_SUFFIX}\"}"
+  # Build JSON response
+  local response="{\"port\":${port},\"fqdn\":\"${project}.${DOMAIN_SUFFIX}\""
+  if [ "$routing_mode" = "subdomain" ]; then
+    response="${response},\"routing_mode\":\"subdomain\""
+    response="${response},\"subdomains\":{\"forge\":\"forge.${project}.${DOMAIN_SUFFIX}\",\"ci\":\"ci.${project}.${DOMAIN_SUFFIX}\",\"chat\":\"chat.${project}.${DOMAIN_SUFFIX}\"}"
+  fi
+  response="${response}}"
+  echo "$response"
 }
 
 # Deregister a tunnel
@@ -109,9 +121,18 @@ do_deregister() {
   # Remove from registry
   free_port "$project" >/dev/null
 
-  # Remove Caddy route
+  # Remove Caddy route for main project domain
   remove_route "$project"
 
+  # Subdomain mode: also remove per-service subdomain routes
+  local routing_mode="${EDGE_ROUTING_MODE:-subpath}"
+  if [ "$routing_mode" = "subdomain" ]; then
+    local subdomain
+    for subdomain in forge ci chat; do
+      remove_route "${subdomain}.${project}"
+    done
+  fi
+
   # Rebuild authorized_keys for tunnel user
   rebuild_authorized_keys