setup: Add script to share agent state via container home symlinks

setup.sh

@@ -0,0 +1,105 @@
+#!/usr/bin/env bash
+#
+# Set up shared agent state for agent-container.
+#
+# Moves agent state (Claude Code, Pi, OpenCode) from the real $HOME into the
+# container home and symlinks it back, so the containerized tools (claude, pi,
+# opencode) and the local variants (claude-local, pi-local, opencode-local)
+# share logins, settings, and history. See README.md, section "Sharing agent
+# state between host and container via symlinks".
+#
+# Safe to re-run: already shared items are detected and left alone.
+
+set -euo pipefail
+
+XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"
+CONTAINER_HOME="$XDG_DATA_HOME/agent-container/container-home"
+
+# State directories to share. Created in the container home (and linked into
+# $HOME) even if they don't exist yet, so both sides share from the start.
+DIRS=(
+    .claude
+    .pi
+    .agents
+    .config/opencode
+    .local/share/opencode
+)
+
+# Single files to share. Only linked when they exist on one side, tools create
+# them on first use.
+FILES=(
+    .claude.json
+)
+
+info() { printf '  %s\n' "$*"; }
+warn() { printf '  warning: %s\n' "$*" >&2; }
+
+# Print the action taken for an item, shared by both helpers below.
+_report() {
+    local action="$1" item="$2"
+    case "$action" in
+        moved)   info "moved   $item into the container home, symlinked from \$HOME" ;;
+        linked)  info "linked  $item (container home already had it)" ;;
+        created) info "created $item in the container home, symlinked from \$HOME" ;;
+        ok)      info "ok      $item (already shared)" ;;
+        skip)    info "skip    $item (does not exist yet, the tool will create it)" ;;
+    esac
+}
+
+share_item() {
+    local item="$1" must_exist="$2"
+    local host="$HOME/$item" target="$CONTAINER_HOME/$item"
+
+    if [ -L "$host" ]; then
+        case "$(readlink -f "$host")" in
+            "$CONTAINER_HOME"/*)
+                _report ok "$item"
+                return
+                ;;
+            *)
+                warn "$item is a symlink to $(readlink "$host"), not touching it"
+                return
+                ;;
+        esac
+    fi
+
+    if [ -e "$host" ] && [ -e "$target" ]; then
+        warn "$item exists in both \$HOME and the container home"
+        warn "reconcile the two copies manually, then re-run this script"
+        return
+    fi
+
+    if [ ! -e "$host" ] && [ ! -e "$target" ]; then
+        if [ "$must_exist" = "yes" ]; then
+            _report skip "$item"
+            return
+        fi
+        mkdir -p "$target"
+        _report created "$item"
+    elif [ -e "$host" ]; then
+        mkdir -p "$(dirname "$target")"
+        mv "$host" "$target"
+        _report moved "$item"
+    else
+        _report linked "$item"
+    fi
+
+    mkdir -p "$(dirname "$host")"
+    ln -s "$target" "$host"
+}
+
+main() {
+    printf 'Sharing agent state via %s\n\n' "$CONTAINER_HOME"
+
+    local item
+    for item in "${DIRS[@]}";  do share_item "$item" no;  done
+    for item in "${FILES[@]}"; do share_item "$item" yes; done
+
+    if [ -f "$HOME/.gitconfig" ] && [ ! -e "$CONTAINER_HOME/.gitconfig" ]; then
+        printf '\n'
+        info "Tip: share your git config too (see README):"
+        info "  ln $HOME/.gitconfig $CONTAINER_HOME/.gitconfig"
+    fi
+}
+
+main "$@"