Add INSTALL_PI build arg for pi as second harness

Optional integration of pi-coding-agent alongside opencode in the same
container. Both harnesses share the mempalace install and palace path —
wing/diary entries are mutually visible.

Build:
  --build-arg INSTALL_PI=true              # opt-in
  --build-arg PI_VERSION=0.73.1            # pin a version (default: latest)
  --build-arg INSTALL_OPENCODE=false       # build pi-only image

Dockerfile:
  • New INSTALL_PI block: npm install -g @mariozechner/pi-coding-agent
    + git-clones pi-toolkit and pi-extensions to /opt/.
  • Existing opencode install gated behind new INSTALL_OPENCODE arg
    (default true; existing builds unaffected).
  • mkdir adds ~/.pi/agent/extensions for the named volume mount root.
  • CMD changed from ['opencode'] to ['bash', '-l']. compose run --rm
    devbox now drops to a login shell so users pick the harness; pass
    'opencode' or 'pi' explicitly to launch directly. compose exec
    workflows are unaffected (bypass entrypoint+CMD).

entrypoint.sh:
  • Adds ~/.pi to volume ownership loop.

entrypoint-user.sh:
  • New 'pi: deploy toolkit + extensions + mempalace bridge' block runs
    pi-toolkit/install.sh, pi-extensions/install.sh, settings.json
    template bootstrap, then symlinks the mempalace.ts bridge directly.
    Order: toolkit before extensions before bridge. mempalace-toolkit's
    full install.sh is intentionally NOT called (its install_skill
    would race with skillset auto-deploy --prune-stale).

docker-compose.yml:
  • New devbox-pi-config named volume mounted at /home/developer/.pi.
    Persists user toggles (/ext-disabled extensions) and settings.json
    edits across container recreate. Mirrors devbox-opencode-config
    pattern from v1.14.33.

scripts/smoke-test.sh:
  • New --variant with-pi (threshold 2700 MB) and --variant omos-with-pi
    (3400 MB).
  • Pi assertions gated on `command -v pi`: version, /opt/pi-toolkit
    clone HEAD, /opt/pi-extensions clone HEAD, deployed keybindings
    symlink, ≥4 extension symlinks, mempalace.ts bridge symlink,
    settings.json bootstrap.
  • Pi state assertions use docker exec from the host (not 'run'),
    since the container has no docker CLI.
  • opencode core test now gated on INSTALL_OPENCODE presence.

scripts/generate-dockerhub-md.py:
  • SECTION_RULES adds 'pi (alternative/complementary harness)': drop.
    Section stays in README; dropped from DOCKER_HUB.md to keep under
    the 25 kB Docker Hub limit.

Docs:
  • README adds full 'pi (alternative/complementary harness)' section.
  • AGENTS.md codifies pi install contract, deploy ordering, named
    volume rationale, and CMD change.
  • CHANGELOG.md gets an Unreleased entry.
  • .env.example documents new build args.
  • docker-compose.yml example args block updated.

Verification (local builds on arm64):
  • Default (INSTALL_PI=false): 1871 MB, all assertions pass — no
    regression.
  • INSTALL_PI=true: 2110 MB (within 2700 threshold), 37 assertions
    pass including pi version, all 7 extensions deployed (6 from
    pi-extensions + mempalace.ts bridge), settings.json bootstrap.

Not yet:
  • CI workflow updates to add -with-pi tag variants. Deferred until
    local path stabilizes through user testing.
  • pi-devbox separate repo for fully stripped pi-only image. Phase 2.

entrypoint-user.sh

@@ -44,6 +44,44 @@ fi
 # generated) and no-ops if OPENCODE_PROVIDER is unset.
 python3 /usr/local/lib/opencode-devbox/generate-config.py
 
+# ── pi: deploy toolkit + extensions + mempalace bridge ─────────────
+# Runs only when pi was baked into the image (INSTALL_PI=true at build).
+# Each install.sh is idempotent and backs up real files before linking,
+# so re-running across container restarts is safe.
+#
+# Order: pi-toolkit first (creates ~/.pi/agent/keybindings.json symlink
+# and writes the AWS env loader), then pi-extensions (symlinks our 6
+# extensions), then settings.json bootstrap from the toolkit template,
+# then the mempalace bridge symlink (one-liner; mempalace-toolkit's
+# install_skill is intentionally skipped to avoid racing with skillset
+# auto-deploy below).
+if command -v pi &>/dev/null; then
+  if [ -d /opt/pi-toolkit ]; then
+    (cd /opt/pi-toolkit && ./install.sh --yes) || \
+      echo "WARN: pi-toolkit install.sh failed (continuing)"
+  fi
+
+  if [ -d /opt/pi-extensions ]; then
+    (cd /opt/pi-extensions && ./install.sh --yes) || \
+      echo "WARN: pi-extensions install.sh failed (continuing)"
+  fi
+
+  # Bootstrap settings.json from template if absent (pi rewrites this
+  # file at runtime — lastChangelogVersion, etc — so we can't symlink it).
+  if [ ! -f "$HOME/.pi/agent/settings.json" ] && \
+     [ -f /opt/pi-toolkit/settings.example.json ]; then
+    cp /opt/pi-toolkit/settings.example.json "$HOME/.pi/agent/settings.json"
+  fi
+
+  # pi↔mempalace MCP bridge — single extension symlink.
+  if [ -f /opt/mempalace-toolkit/extensions/pi/mempalace.ts ] && \
+     command -v mempalace &>/dev/null && \
+     [ ! -L "$HOME/.pi/agent/extensions/mempalace.ts" ]; then
+    ln -sf /opt/mempalace-toolkit/extensions/pi/mempalace.ts \
+           "$HOME/.pi/agent/extensions/mempalace.ts"
+  fi
+fi
+
 # ── Skillset: deploy skills/instructions from mounted skillset repo ──
 # When the skillset repo is mounted (at $HOME/skillset or /workspace/skillset),
 # run the deploy script to create relative symlinks for skills and instructions.