diff --git a/TODO.md b/TODO.md
index e031fac..34b18db 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,30 @@
 # TODO
 
+## Ghostty config standardization
+
+The ghostty config lives in two places (`macOS/ghostty.config`, `linux-desktop/ghostty.config`)
+with identical content. Consider extracting a universal `cross-platform/ghostty.config` for shared
+settings (`term = xterm-256color`, `theme`, `shell-integration`) and keeping OS-specific
+configs additive-only (e.g., macOS font settings, Linux-specific tweaks).
+
+- [ ] Create `cross-platform/ghostty.config` (universal base)
+- [ ] Refactor OS configs to extend/override the universal base
+- [ ] Update both `setup.sh` scripts to deploy the new layout (universal + OS overlay)
+
+## OpenCode local models
+
+Config uses `mlx_lm.server` with Qwen 3.5 9B (4bit, MLX) on the Mac Mini M4.
+`opencode-local` script auto-discovers models in `~/.models/`, starts the
+server, and launches OpenCode.
+
+Still to explore:
+
+- [ ] Test tool-calling quality with Qwen 3.5 9B (does it work well for agentic coding?)
+- [ ] Set up on CachyOS/AMD R9700 with Gemma 4 and Qwen 3.6 (via llama.cpp or lemonade)
+- [ ] Add CachyOS provider config once the model/runtime is chosen
+- [ ] Consider `small_model` for lightweight tasks (title gen, etc.)
+- [ ] Install `opencode-local` via install.sh and verify PATH
+
 ## macOS zshrc modernization
 
 Port the linux-desktop zsh enhancements to the macOS config. See
diff --git a/agentic-ai/OpenCode/README.md b/agentic-ai/OpenCode/README.md
new file mode 100644
index 0000000..7483dc5
--- /dev/null
+++ b/agentic-ai/OpenCode/README.md
@@ -0,0 +1,88 @@
+# OpenCode Config
+
+Version-controlled source of truth for `~/.config/opencode/opencode.json`.
+Running `install.sh` wires everything up via symlinks so changes here take
+effect immediately.
+
+## Activation
+
+```bash
+bash agentic-ai/OpenCode/install.sh
+```
+
+This will:
+- Back up your existing `~/.config/opencode/opencode.json` (if not already a symlink)
+- Symlink `~/.config/opencode/opencode.json` → this `opencode.json`
+- Symlink `bin/opencode-local` → `~/.local/bin/opencode-local`
+
+Restart OpenCode after running.
+
+## Usage
+
+### Launch with model picker
+
+```bash
+opencode-local
+```
+
+This scans `~/.models/` for MLX model directories, lets you pick one, starts
+the server, waits for it to be ready, then launches OpenCode. The server
+shuts down automatically when you exit OpenCode.
+
+Pass through additional OpenCode flags:
+
+```bash
+opencode-local --model anthropic/claude-sonnet-4-6
+```
+
+### Launch manually
+
+```bash
+mlx_lm.server --model ~/.models/mlx-community--Qwen3.5-9B-4bit &
+opencode
+# kill %1 when done
+```
+
+### Model selection in OpenCode
+
+Once connected to a server, select the model via:
+
+```
+/models
+```
+
+Pick `mlx/mlx-community/Qwen3.5-9B-4bit` (or whichever model the server has
+loaded).
+
+## Recommended models
+
+| Machine | Model | Notes |
+|---------|-------|-------|
+| Mac Mini M4 | **Qwen 3.5 9B (4bit)** — `~/.models/mlx-community--Qwen3.5-9B-4bit` | MLX-optimized, already on this machine |
+| CachyOS / AMD R9700 AI PRO | **Gemma 4** / **Qwen 3.6** (larger variants) | Powerful AMD GPU — test these on the desktop |
+
+## Usage alongside Claude
+
+OpenCode supplements Claude Code for:
+- **Small, fast edits** that don't need Claude's full context
+- **Exploratory work** on unfamiliar code
+- **Offline-capable tasks** when you're not connected
+- **Private/air-gapped work** where code shouldn't leave the machine
+
+Claude Code handles complex multi-file refactors, architecture decisions,
+and heavy debugging.
+
+## What this configures
+
+### MLX provider
+
+Registers `mlx_lm.server` (OpenAI-compatible endpoint at
+`http://127.0.0.1:8080/v1`) as a provider with pre-configured model entries.
+Add or remove models by editing `opencode.json` directly — the symlink means
+changes are live immediately after restarting OpenCode.
+
+### `opencode-local` command
+
+A wrapper script that scans `~/.models/` for MLX model directories, presents
+a picker, starts the server, and launches OpenCode. On exit, the server is
+cleaned up automatically.
diff --git a/agentic-ai/OpenCode/bin/opencode-local b/agentic-ai/OpenCode/bin/opencode-local
new file mode 100755
index 0000000..1f9e895
--- /dev/null
+++ b/agentic-ai/OpenCode/bin/opencode-local
@@ -0,0 +1,155 @@
+#!/usr/bin/env bash
+# Launch OpenCode with a local MLX model.
+# Scans ~/.models/ for MLX model dirs, lets you pick one, starts the server,
+# waits for it to be ready, then launches OpenCode. Cleans up on exit.
+#
+# Usage:  opencode-local [opencode-args...]
+#         opencode-local --log          # tail the server log
+
+set -euo pipefail
+
+MODELS_DIR="${MLX_MODELS_DIR:-$HOME/.models}"
+SERVER_HOST="${MLX_HOST:-127.0.0.1}"
+SERVER_PORT="${MLX_PORT:-8080}"
+SERVER_URL="http://${SERVER_HOST}:${SERVER_PORT}"
+LOG_DIR="${XDG_STATE_HOME:-$HOME/.local/share}/opencode-local"
+LOG_FILE="$LOG_DIR/server.log"
+
+mkdir -p "$LOG_DIR"
+
+# Log a timestamped message to the log file
+log() {
+  printf '[%s] %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" >> "$LOG_FILE"
+}
+
+# ── discover models ──────────────────────────────────────────────────────
+
+discover_models() {
+  local entries=()
+  for dir in "$MODELS_DIR"/mlx-community--*; do
+    [[ -d "$dir" ]] || continue
+    local name="${dir##*/}"            # mlx-community--Qwen3.5-9B-4bit
+    local display="${name#mlx-community--}"  # Qwen3.5-9B-4bit
+    # Pretty-print: replace dashes with spaces, wrap trailing bit in parens
+    display="${display//-/ }"
+    # Extract trailing "Nbit" and wrap in parens (bash 3.2 compat)
+    local bits="${display##* }"
+    display="${display% $bits}"
+    display="$display ($bits)"
+    entries+=("$dir|$display")
+  done
+  printf '%s\n' "${entries[@]}"
+}
+
+# ── model picker ──────────────────────────────────────────────────────────
+
+pick_model() {
+  local -a models=()
+  while IFS= read -r line; do
+    models+=("$line")
+  done < <(discover_models | sort -t'|' -k2)
+
+  if [[ ${#models[@]} -eq 0 ]]; then
+    printf 'No MLX models found in %s\n' "$MODELS_DIR" >&2
+    printf 'Pull one first:\n' >&2
+    printf '  huggingface-cli download mlx-community/Qwen3.5-9B-4bit --local-dir ~/.models/mlx-community--Qwen3.5-9B-4bit\n' >&2
+    exit 1
+  fi
+
+  if [[ ${#models[@]} -eq 1 ]]; then
+    # Only one model — use it without prompting
+    IFS='|' read -r selected_path selected_name <<< "${models[0]}"
+    printf 'Using model: %s\n' "$selected_name" >&2
+    printf '%s\n' "$selected_path"
+    return
+  fi
+
+  printf '\nAvailable models:\n' >&2
+  for i in "${!models[@]}"; do
+    IFS='|' read -r _ name <<< "${models[$i]}"
+    printf '  [%d] %s\n' $((i + 1)) "$name" >&2
+  done
+  printf '\nSelect model [1-%d]: ' "${#models[@]}" >&2
+
+  local choice
+  read -r choice
+  if [[ ! "$choice" =~ ^[0-9][0-9]*$ ]] || (( choice < 1 || choice > ${#models[@]} )); then
+    printf 'Invalid selection\n' >&2
+    exit 1
+  fi
+
+  IFS='|' read -r selected_path selected_name <<< "${models[$((choice - 1))]}"
+  printf 'Using model: %s\n' "$selected_name" >&2
+  printf '%s\n' "$selected_path"
+}
+
+# ── wait for server ───────────────────────────────────────────────────────
+
+wait_for_server() {
+  local max_attempts=60  # 30 seconds
+  local attempt=0
+  while ! curl -sf "$SERVER_URL/v1/models" >/dev/null 2>&1; do
+    attempt=$((attempt + 1))
+    if (( attempt > max_attempts )); then
+      log "Server failed to start within $((max_attempts / 2)) seconds"
+      printf '\nServer failed to start within %d seconds\n' "$((max_attempts / 2))" >&2
+      printf 'Check the log for details: %s\n' "$LOG_FILE" >&2
+      exit 1
+    fi
+    printf '\rWaiting for model server to be ready... (%ds)' "$((attempt / 2))"
+    sleep 0.5
+  done
+  printf '\rModel server ready%s\n' '                         '
+}
+
+# ── main ──────────────────────────────────────────────────────────────────
+
+# --log flag: just tail the log file
+if [[ "${1:-}" == "--log" ]]; then
+  if [[ -f "$LOG_FILE" ]]; then
+    tail -f "$LOG_FILE"
+  else
+    printf 'No log file yet at: %s\n' "$LOG_FILE" >&2
+    exit 1
+  fi
+  exit 0
+fi
+
+MODEL_PATH="$(pick_model)"
+log "Selected model: $MODEL_PATH"
+log "Starting MLX server (host=$SERVER_HOST port=$SERVER_PORT)"
+
+printf 'Starting MLX server with: %s\n' "$MODEL_PATH"
+
+# Start the server in the background, tee stderr to log
+mlx_lm.server \
+  --model "$MODEL_PATH" \
+  --host "$SERVER_HOST" \
+  --port "$SERVER_PORT" \
+  --max-tokens 4096 \
+  --prompt-cache-bytes 4294967296 \
+  --log-level ERROR \
+  2>>"$LOG_FILE" &
+
+SERVER_PID=$!
+log "Server PID: $SERVER_PID"
+
+# Cleanup on exit
+cleanup() {
+  local exit_code=$?
+  if [[ $exit_code -ne 0 ]]; then
+    log "Exited with code $exit_code — see log: $LOG_FILE"
+  fi
+  log "Shutting down server (PID $SERVER_PID)"
+  printf '\nShutting down model server...\n'
+  kill "$SERVER_PID" 2>/dev/null || true
+  wait "$SERVER_PID" 2>/dev/null || true
+  log "Server stopped"
+}
+trap cleanup EXIT INT TERM
+
+wait_for_server
+log "Server ready"
+
+# Launch OpenCode — pass through any extra args
+opencode "$@"
diff --git a/agentic-ai/OpenCode/install.sh b/agentic-ai/OpenCode/install.sh
new file mode 100755
index 0000000..dd2e8d2
--- /dev/null
+++ b/agentic-ai/OpenCode/install.sh
@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+# Idempotent setup: symlinks this repo's OpenCode config into ~/.config/opencode/
+# Safe to re-run. Backs up any existing opencode.json before replacing it.
+
+set -euo pipefail
+
+REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+OPENCODE_DIR="$HOME/.config/opencode"
+CONFIG="$OPENCODE_DIR/opencode.json"
+
+printf 'Installing from: %s\n' "$REPO_DIR"
+
+mkdir -p "$OPENCODE_DIR"
+
+# Back up opencode.json if it exists and is not already one of ours
+if [[ -e "$CONFIG" && ! -L "$CONFIG" ]]; then
+  BACKUP="$CONFIG.bak.$(date +%Y%m%d%H%M%S)"
+  printf 'Backing up existing opencode.json → %s\n' "$BACKUP"
+  mv "$CONFIG" "$BACKUP"
+fi
+
+ln -sf "$REPO_DIR/opencode.json" "$CONFIG"
+printf 'Linked: opencode.json\n'
+
+# Symlink launch script into PATH
+LOCAL_BIN="$HOME/.local/bin"
+mkdir -p "$LOCAL_BIN"
+ln -sf "$REPO_DIR/bin/opencode-local" "$LOCAL_BIN/opencode-local"
+printf 'Linked: bin/opencode-local → %s/opencode-local\n' "$LOCAL_BIN"
+
+printf '\nDone. Restart OpenCode for changes to take effect.\n'
diff --git a/agentic-ai/OpenCode/opencode.json b/agentic-ai/OpenCode/opencode.json
new file mode 100644
index 0000000..8cb8ead
--- /dev/null
+++ b/agentic-ai/OpenCode/opencode.json
@@ -0,0 +1,17 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "provider": {
+    "mlx": {
+      "npm": "@ai-sdk/openai-compatible",
+      "name": "MLX (local)",
+      "options": {
+        "baseURL": "http://127.0.0.1:8080/v1"
+      },
+      "models": {
+        "mlx-community/Qwen3.5-9B-4bit": {
+          "name": "Qwen 3.5 9B (4bit, MLX)"
+        }
+      }
+    }
+  }
+}
diff --git a/linux-desktop/ghostty.config b/linux-desktop/ghostty.config
index 343919f..a60cb99 100644
--- a/linux-desktop/ghostty.config
+++ b/linux-desktop/ghostty.config
@@ -2,3 +2,4 @@
 
 theme = Dark Pastel
 shell-integration = zsh
+term = xterm-256color
diff --git a/macOS/ghostty.config b/macOS/ghostty.config
index 343919f..a60cb99 100644
--- a/macOS/ghostty.config
+++ b/macOS/ghostty.config
@@ -2,3 +2,4 @@
 
 theme = Dark Pastel
 shell-integration = zsh
+term = xterm-256color
diff --git a/macOS/setup.sh b/macOS/setup.sh
index 42151aa..cc19774 100755
--- a/macOS/setup.sh
+++ b/macOS/setup.sh
@@ -229,6 +229,10 @@ else
   fi
 fi
 
+# ── Git: GPG signing ─────────────────────────────────────────────────────────
+run git config --global gpg.program /opt/homebrew/bin/gpg
+add_to_zshrc 'export GPG_TTY=$(tty)'
+
 # ── Medium-priority pipx packages ─────────────────────────────────────────────
 echo "==> Installing pipx packages..."
 if [[ "$DRY_RUN" == false ]]; then
diff --git a/macOS/zshrc.example b/macOS/zshrc.example
index 6027838..dcd9163 100644
--- a/macOS/zshrc.example
+++ b/macOS/zshrc.example
@@ -98,6 +98,7 @@ alias gl='git log --oneline --graph --decorate'
 export EDITOR='micro'
 export LANG='en_US.UTF-8'
 export LC_ALL='en_US.UTF-8'
+export GPG_TTY=$(tty)
 
 
 # ═══════════════════════════════════════════════════════════════