feat: add multi-runtime support (coord run, prdy --codex) and next-task capsule

- coord/prdy subcommands now accept --claude/--codex runtime flags
- New `mosaic coord run` generates continuation context and launches
  selected runtime, replacing manual copy/paste workflow
- Next-task capsule (.mosaic/orchestrator/next-task.json) provides
  machine-readable execution context for deterministic session launches
- Codex strict orchestrator profile added to runtime/codex/RUNTIME.md
- Orchestrator protocol updated with between-session run flow
- New smoke-test.sh for orchestration behavior verification

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/orchestrator/_lib.sh

@@ -11,6 +11,7 @@ MOSAIC_HOME="${MOSAIC_HOME:-$HOME/.config/mosaic}"
 ORCH_SUBDIR=".mosaic/orchestrator"
 MISSION_FILE="mission.json"
 SESSION_LOCK_FILE="session.lock"
+NEXT_TASK_FILE="next-task.json"
 MANIFEST_FILE="docs/MISSION-MANIFEST.md"
 TASKS_MD="docs/TASKS.md"
 SCRATCHPAD_DIR="docs/scratchpads"
@@ -42,6 +43,30 @@ _require_jq() {
   fi
 }
 
+coord_runtime() {
+  local runtime="${MOSAIC_COORD_RUNTIME:-claude}"
+  case "$runtime" in
+    claude|codex) echo "$runtime" ;;
+    *) echo "claude" ;;
+  esac
+}
+
+coord_launch_command() {
+  local runtime
+  runtime="$(coord_runtime)"
+  echo "mosaic $runtime"
+}
+
+coord_run_command() {
+  local runtime
+  runtime="$(coord_runtime)"
+  if [[ "$runtime" == "claude" ]]; then
+    echo "mosaic coord run"
+  else
+    echo "mosaic coord run --$runtime"
+  fi
+}
+
 # ─── Project / state file access ────────────────────────────────────────────
 
 # Return the orchestrator directory for a project
@@ -56,6 +81,11 @@ mission_path() {
   echo "$(orch_dir "$project")/$MISSION_FILE"
 }
 
+next_task_capsule_path() {
+  local project="${1:-.}"
+  echo "$(orch_dir "$project")/$NEXT_TASK_FILE"
+}
+
 # Exit with error if mission.json is missing or inactive
 require_mission() {
   local project="${1:-.}"
@@ -358,6 +388,113 @@ milestone_name() {
   jq -r --arg id "$mid" '.milestones[] | select(.id == $id) | .name // empty' "$mp"
 }
 
+# ─── Next-task capsule helpers ───────────────────────────────────────────────
+
+write_next_task_capsule() {
+  local project="${1:-.}"
+  local runtime="${2:-claude}"
+  local mission_id="${3:-}"
+  local mission_name="${4:-}"
+  local project_path="${5:-}"
+  local quality_gates="${6:-}"
+  local current_ms_id="${7:-}"
+  local current_ms_name="${8:-}"
+  local next_task="${9:-}"
+  local tasks_done="${10:-0}"
+  local tasks_total="${11:-0}"
+  local pct="${12:-0}"
+  local current_branch="${13:-}"
+
+  _require_jq || return 1
+  mkdir -p "$(orch_dir "$project")"
+
+  local payload
+  payload="$(jq -n \
+    --arg generated_at "$(iso_now)" \
+    --arg runtime "$runtime" \
+    --arg mission_id "$mission_id" \
+    --arg mission_name "$mission_name" \
+    --arg project_path "$project_path" \
+    --arg quality_gates "$quality_gates" \
+    --arg current_ms_id "$current_ms_id" \
+    --arg current_ms_name "$current_ms_name" \
+    --arg next_task "$next_task" \
+    --arg current_branch "$current_branch" \
+    --arg tasks_done "$tasks_done" \
+    --arg tasks_total "$tasks_total" \
+    --arg pct "$pct" \
+    '{
+      generated_at: $generated_at,
+      runtime: $runtime,
+      mission_id: $mission_id,
+      mission_name: $mission_name,
+      project_path: $project_path,
+      quality_gates: $quality_gates,
+      current_milestone: {
+        id: $current_ms_id,
+        name: $current_ms_name
+      },
+      next_task: $next_task,
+      progress: {
+        tasks_done: ($tasks_done | tonumber),
+        tasks_total: ($tasks_total | tonumber),
+        pct: ($pct | tonumber)
+      },
+      current_branch: $current_branch
+    }')"
+
+  write_json "$(next_task_capsule_path "$project")" "$payload"
+}
+
+build_codex_strict_kickoff() {
+  local project="${1:-.}"
+  local continuation_prompt="${2:-}"
+
+  _require_jq || return 1
+
+  local capsule_path
+  capsule_path="$(next_task_capsule_path "$project")"
+  local capsule='{}'
+  if [[ -f "$capsule_path" ]]; then
+    capsule="$(cat "$capsule_path")"
+  fi
+
+  local mission_id next_task project_path quality_gates
+  mission_id="$(echo "$capsule" | jq -r '.mission_id // "unknown"')"
+  next_task="$(echo "$capsule" | jq -r '.next_task // "none"')"
+  project_path="$(echo "$capsule" | jq -r '.project_path // "."')"
+  quality_gates="$(echo "$capsule" | jq -r '.quality_gates // "none"')"
+
+  cat <<EOF
+Now initiating Orchestrator mode...
+
+STRICT EXECUTION PROFILE FOR CODEX (HARD GATE)
+- Do NOT ask clarifying questions before your first tool actions unless a Mosaic escalation trigger is hit.
+- Your first actions must be reading mission state files in order.
+- Treat the next-task capsule as authoritative execution input.
+
+REQUIRED FIRST ACTIONS (IN ORDER)
+1. Read ~/.config/mosaic/guides/ORCHESTRATOR-PROTOCOL.md
+2. Read docs/MISSION-MANIFEST.md
+3. Read docs/scratchpads/${mission_id}.md
+4. Read docs/TASKS.md
+5. Begin execution on next task: ${next_task}
+
+WORKING CONTEXT
+- Project: ${project_path}
+- Quality gates: ${quality_gates}
+- Capsule file: .mosaic/orchestrator/next-task.json
+
+Task capsule (JSON):
+\`\`\`json
+${capsule}
+\`\`\`
+
+Continuation prompt:
+${continuation_prompt}
+EOF
+}
+
 # Get next milestone after the given one
 next_milestone_id() {
   local project="${1:-.}"