diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 33819df..578feba 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,7 +11,7 @@ cd devloop
 devloop doctor         # verify required dependencies
 ```
 
-Required to run a loop: Bash, git, `glow`, `gum`, `fzf`, and the `codex` and `claude` CLIs. The install scripts use Homebrew to install missing git/UI tools and the Codex/Claude Code casks when `brew` is available. The test suite itself needs only Bash, git, and coreutils, so you can develop and test without the agent CLIs installed.
+Required to run a loop: Bash, git, `glow`, `gum`, `fzf`, `tmux`, and the `codex` and `claude` CLIs. The install scripts use Homebrew to install missing git/UI tools and tmux, plus the Codex/Claude Code casks when `brew` is available. Interactive runs enter a named tmux session by default; use `--no-tmux` when debugging the foreground process. The test suite itself needs only Bash, git, and coreutils because tmux behavior is covered with a fake executable.
 
 ## Development loop
 
diff --git a/README.md b/README.md
index 95b4626..e30ab31 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ cd devloop
 ./scripts/install.sh
 ```
 
-> Requires Bash, git, `codex`, `claude`, `glow`, `gum`, and `fzf`. Run `devloop doctor` to check.
+> Requires Bash, git, `codex`, `claude`, `glow`, `gum`, `fzf`, and `tmux`. Run `devloop doctor` to check.
 > The installers use Homebrew to install missing git/UI tools and the Codex/Claude Code casks when `brew` is available.
 
 Uninstall with `./scripts/uninstall.sh` (`--dry-run` to preview).
@@ -40,6 +40,7 @@ Uninstall with `./scripts/uninstall.sh` (`--dry-run` to preview).
 | `devloop spec "..."` | Have an agent interview you and write a spec |
 | `devloop nightshift` | Survey configured repos, run selected specs headlessly, and write a morning digest |
 | `devloop <spec.md>` | Run a spec |
+| `devloop --no-tmux <spec.md>` | Run a spec in the current foreground terminal |
 | `devloop --create-pr <spec.md>` | Run a spec and maintain a draft PR (requires `gh`) |
 | `devloop update` | Install the latest released Devloop |
 | `devloop continue` | Resume a tracked run |
@@ -49,6 +50,8 @@ Uninstall with `./scripts/uninstall.sh` (`--dry-run` to preview).
 Each run writes an HTML report, spec, and reviews under `.devloop/`.
 When you pick a spec from the interactive menu, devloop uses your configured run defaults and only prompts for PR mode. The interactive **Settings** menu sets the default coder and reviewer agents (Codex or Claude Code), spec path, and run timeout, saved to `~/.devloop/config`. Use CLI flags such as `--coder`, `--reviewer`, `--in-place`, or `--timeout-minutes` to override those defaults per run.
 
+Interactive run and continue workflows start in a new named tmux session by default. Detach without stopping devloop with `Ctrl-b d`, list sessions with `tmux list-sessions`, and reconnect with `tmux attach -t <session>`. Pass `--no-tmux` to an explicit run or continue command to keep the existing foreground behavior. Redirected, piped, and scheduled runs stay in the foreground automatically.
+
 ## Specs
 
 A good spec is short, concrete, and verifiable. It includes a repository-grounded implementation map, invariants, credible failure modes, and a proof map linking every obligation to test evidence. Start from [`skills/devloop-spec/references/spec-template.md`](skills/devloop-spec/references/spec-template.md). The bundled `devloop-spec` skill can also render a sibling HTML companion with [`skills/devloop-spec/scripts/render.sh`](skills/devloop-spec/scripts/render.sh).
diff --git a/devloop b/devloop
index 583c66c..1b9d663 100755
--- a/devloop
+++ b/devloop
@@ -210,6 +210,7 @@ Common commands:
 Options:
   --tui                         force terminal UI output
   --plain                       force plain output
+  --no-tmux                     run in the foreground without tmux
   --coder codex|claude          choose Codex or Claude Code for implementation (default from Settings)
   --reviewer codex|claude       choose Codex or Claude Code for review (default from Settings)
   --report-format html|markdown choose report format
@@ -221,6 +222,9 @@ Options:
   --shell, --enter-worktree     open a shell in the run worktree after completion
   -V, --version                 show version
   -h, --help                    show this screen
+
+Interactive run and continue commands start in a named tmux session.
+Detach with Ctrl-b d; reattach with tmux attach -t <session>.
 EOF
 }
 
@@ -247,6 +251,7 @@ welcome_tui() {
   gum style --foreground "$UI_ACCENT_COLOR" --bold "Options"
   printf '  %-30s %s\n' "--tui" "force terminal UI output"
   printf '  %-30s %s\n' "--plain" "force plain output"
+  printf '  %-30s %s\n' "--no-tmux" "run in the foreground without tmux"
   printf '  %-30s %s\n' "--coder codex|claude" "choose implementation agent (default from Settings)"
   printf '  %-30s %s\n' "--reviewer codex|claude" "choose review agent (default from Settings)"
   printf '  %-30s %s\n' "--report-format html|markdown" "choose report format"
@@ -258,10 +263,12 @@ welcome_tui() {
   printf '  %-30s %s\n' "--shell, --enter-worktree" "open a shell after completion"
   printf '  %-30s %s\n' "-V, --version" "show version"
   printf '  %-30s %s\n' "-h, --help" "show this screen"
+  printf '\n%s\n' "Interactive run and continue commands start in a named tmux session."
+  printf '%s\n' "Detach with Ctrl-b d; reattach with tmux attach -t <session>."
 }
 
 usage() {
-  printf '%s\n' "usage: devloop [--version] [--plain|--tui] [--in-place] [--no-strict] [--create-pr|--pr] [--no-shell|--stay|--shell|--enter-worktree] [--coder codex|claude] [--reviewer codex|claude] [--report-format html|markdown] [--timeout-minutes N] <spec.md> [max=5]"
+  printf '%s\n' "usage: devloop [--version] [--plain|--tui] [--no-tmux] [--in-place] [--no-strict] [--create-pr|--pr] [--no-shell|--stay|--shell|--enter-worktree] [--coder codex|claude] [--reviewer codex|claude] [--report-format html|markdown] [--timeout-minutes N] <spec.md> [max=5]"
   printf '%s\n' "agents: Codex or Claude Code"
 }
 
@@ -288,6 +295,92 @@ has_arg() {
   return 1
 }
 
+devloop_tmux_interactive() {
+  [ -t 0 ] && [ -t 1 ]
+}
+
+tmux_normalize_component() {
+  local value="$1"
+  local fallback="$2"
+  value="$(printf '%s\n' "$value" |
+    LC_ALL=C tr '[:upper:]' '[:lower:]' |
+    sed -E 's/[^a-z0-9]+/-/g; s/^-+//; s/-+$//')"
+  if [ -z "$value" ]; then value="$fallback"; fi
+  printf '%s\n' "$value"
+}
+
+tmux_session_base_name() {
+  local repo="$1"
+  local source="$2"
+  local repo_name source_name
+  repo_name="$(tmux_normalize_component "$(basename "$repo")" repo)"
+  source_name="$(tmux_normalize_component "$(basename "$source" .md)" run)"
+  printf 'devloop-%s-%s\n' "$repo_name" "$source_name"
+}
+
+tmux_command_available() {
+  command -v tmux >/dev/null 2>&1
+}
+
+tmux_allocate_session_name() {
+  local base="$1"
+  local sessions candidate suffix
+  sessions="$(tmux list-sessions -F '#{session_name}' 2>/dev/null || true)"
+  candidate="$base"
+  suffix=2
+  while printf '%s\n' "$sessions" | grep -Fxq "$candidate"; do
+    candidate="$base-$suffix"
+    suffix=$((suffix + 1))
+  done
+  printf '%s\n' "$candidate"
+}
+
+tmux_launch_session() {
+  local repo="$1"
+  local source="$2"
+  local workflow="$3"
+  shift 3
+  local base session env_command
+  local child=("$SCRIPT_PATH")
+
+  if ! tmux_command_available; then
+    printf '%s\n' "tmux is required for interactive runs; rerun the installer or install tmux with Homebrew." >&2
+    return 1
+  fi
+
+  case "$workflow" in
+    run) child+=(--no-tmux "$@") ;;
+    continue) child+=(continue --no-tmux "$@") ;;
+    *) printf 'unknown tmux workflow: %s\n' "$workflow" >&2; return 2 ;;
+  esac
+
+  base="$(tmux_session_base_name "$repo" "$source")"
+  session="$(tmux_allocate_session_name "$base")"
+  env_command="$(command -v env)" || {
+    printf '%s\n' "unable to resolve env for tmux child launch" >&2
+    return 1
+  }
+
+  if [ -n "${TMUX:-}" ]; then
+    if ! tmux new-session -d -s "$session" -c "$PWD" -- "$env_command" "PATH=$PATH" "${child[@]}"; then
+      printf 'failed to create tmux session: %s\n' "$session" >&2
+      return 1
+    fi
+    if ! tmux switch-client -t "$session"; then
+      printf 'tmux session is still running: %s\n' "$session" >&2
+      printf 'switch with: tmux switch-client -t %s\n' "$session" >&2
+      printf 'attach with: tmux attach -t %s\n' "$session" >&2
+      return 1
+    fi
+    return 0
+  fi
+
+  if ! tmux new-session -s "$session" -c "$PWD" -- "$env_command" "PATH=$PATH" "${child[@]}"; then
+    printf 'failed to create tmux session: %s\n' "$session" >&2
+    return 1
+  fi
+}
+
 version_args_only() {
   local item saw_version=false
   [ "$#" -gt 0 ] || return 1
@@ -1637,6 +1730,8 @@ interactive_run_setup() {
   local max="5"
   local timeout_minutes
   local code
+  local validated_spec repo
+  local tmux_args=()
   coder="$(devloop_coder)"
   reviewer="$(devloop_reviewer)"
   timeout_minutes="$(devloop_timeout_minutes)"
@@ -1650,6 +1745,22 @@ interactive_run_setup() {
     ui_go_back
     return 0
   fi
+  if devloop_tmux_interactive; then
+    validated_spec="$(validate_spec_for_tmux "$spec" "$strict")" || return $?
+    repo="$(git -C "$PWD" rev-parse --show-toplevel 2>/dev/null)" || {
+      printf '%s\n' "not inside a git repository" >&2
+      return 2
+    }
+    if [ "$USE_TUI" = true ]; then tmux_args+=(--tui); else tmux_args+=(--plain); fi
+    tmux_args+=(--report-format "$report_format")
+    if [ "$strict" = true ]; then tmux_args+=(--strict); else tmux_args+=(--no-strict); fi
+    if [ "$use_worktree" != true ]; then tmux_args+=(--in-place); fi
+    if [ "$create_pr" = true ]; then tmux_args+=(--create-pr); fi
+    if [ "$ENTER_WORKTREE" = true ]; then tmux_args+=(--shell); else tmux_args+=(--no-shell); fi
+    tmux_args+=(--coder "$coder" --reviewer "$reviewer" --timeout-minutes "$timeout_minutes" "$spec" "$max")
+    tmux_launch_session "$repo" "$validated_spec" run "${tmux_args[@]}"
+    return $?
+  fi
   run_header "$spec" "$max" "$report_format" "$strict" "$use_worktree" "$coder" "$reviewer" "$create_pr" "$timeout_minutes"
   run_devloop "$spec" "$max" "$report_format" "$strict" "$use_worktree" "$coder" "$reviewer" "$create_pr" "$timeout_minutes"
   code=$?
@@ -1693,7 +1804,7 @@ interactive_open_report() {
 }
 
 interactive_continue_run() {
-  local list selected code
+  local list selected code track repo
   list="$(mktemp "${TMPDIR:-/tmp}/devloop-tracks.XXXXXX")"
   list_artifact_files ".devloop/tracks" > "$list"
   if [ ! -s "$list" ]; then
@@ -1709,7 +1820,15 @@ interactive_continue_run() {
     ui_go_back
     return 0
   fi
-  run_from_track "$selected"
+  track="$(validate_track_for_run "$selected")" || return $?
+  if devloop_tmux_interactive; then
+    repo="$(track_value "source-repo" "$track")"
+    if [ -z "$repo" ]; then repo="$(track_value "worktree" "$track")"; fi
+    if [ -z "$repo" ]; then repo="$PWD"; fi
+    tmux_launch_session "$repo" "$track" continue "$track"
+    return $?
+  fi
+  run_from_track "$track"
 }
 
 reports_command() {
@@ -1832,13 +1951,25 @@ clean_command() {
 }
 
 continue_command() {
-  if [ "$#" -gt 1 ]; then
-    printf '%s\n' "usage: devloop continue [track.md]" >&2
+  local original_args=("$@")
+  local no_tmux=false
+  local positional=()
+  local arg track list selected repo
+  while [ "$#" -gt 0 ]; do
+    arg="$1"
+    shift
+    case "$arg" in
+      --no-tmux) no_tmux=true ;;
+      --*) printf '%s\n' "usage: devloop continue [--no-tmux] [track.md]" >&2; return 2 ;;
+      *) positional+=("$arg") ;;
+    esac
+  done
+  if [ "${#positional[@]}" -gt 1 ]; then
+    printf '%s\n' "usage: devloop continue [--no-tmux] [track.md]" >&2
     return 2
   fi
-  local track list selected
-  if [ "$#" -eq 1 ]; then
-    track="$1"
+  if [ "${#positional[@]}" -eq 1 ]; then
+    track="${positional[0]}"
   else
     list="$(mktemp "${TMPDIR:-/tmp}/devloop-tracks.XXXXXX")"
     list_artifact_files ".devloop/tracks" > "$list"
@@ -1858,6 +1989,18 @@ continue_command() {
     if [ "$code" -ne 0 ] || [ -z "$selected" ]; then return 130; fi
     track="$selected"
   fi
+  track="$(validate_track_for_run "$track")" || return $?
+  if [ "$no_tmux" = false ] && devloop_tmux_interactive; then
+    repo="$(track_value "source-repo" "$track")"
+    if [ -z "$repo" ]; then repo="$(track_value "worktree" "$track")"; fi
+    if [ -z "$repo" ]; then repo="$PWD"; fi
+    if [ "${#original_args[@]}" -eq 0 ]; then
+      tmux_launch_session "$repo" "$track" continue "$track"
+    else
+      tmux_launch_session "$repo" "$track" continue "${original_args[@]}"
+    fi
+    return $?
+  fi
   run_from_track "$track"
 }
 
@@ -2192,7 +2335,7 @@ nightshift_run_spec() {
   mkdir -p "$(dirname "$output")"
   (
     cd "$repo" >/dev/null 2>&1 &&
-      "$runner" --plain --no-shell --create-pr --coder "$coder" --reviewer "$reviewer" --timeout-minutes "$timeout_minutes" "$spec" "$max_passes"
+      "$runner" --plain --no-tmux --no-shell --create-pr --coder "$coder" --reviewer "$reviewer" --timeout-minutes "$timeout_minutes" "$spec" "$max_passes"
   ) > "$output" 2>&1
   code=$?
   status="$(nightshift_result_status "$output" "$code")"
@@ -2654,13 +2797,53 @@ remove_devloop_worktree() {
   fi
 }
 
+validate_track_for_run() {
+  local input="$1"
+  local track worktree spec
+  track="$(absolute_existing_file "$input")" || {
+    printf 'track not found: %s\n' "$input" >&2
+    return 2
+  }
+  worktree="$(track_value "worktree" "$track")"
+  spec="$(track_value "spec" "$track")"
+  if [ -z "$worktree" ]; then worktree="$(cd "$(dirname "$track")/../.." >/dev/null 2>&1 && pwd -P)"; fi
+  if [ -z "$spec" ]; then spec="$(track_value "source-spec" "$track")"; fi
+  if [ ! -d "$worktree" ]; then
+    printf 'worktree not found: %s\n' "$worktree" >&2
+    return 2
+  fi
+  if [ ! -f "$spec" ]; then
+    printf 'spec not found: %s\n' "$spec" >&2
+    return 2
+  fi
+  printf '%s\n' "$track"
+}
+
+validate_spec_for_tmux() {
+  local input="$1"
+  local strict="$2"
+  local spec spec_text criteria_file criteria_count
+  spec="$(absolute_existing_file "$input")" || {
+    usage >&2
+    return 2
+  }
+  spec_text="$(cat "$spec")"
+  criteria_file="$(mktemp "${TMPDIR:-/tmp}/devloop-criteria.XXXXXX")"
+  parse_criteria "$spec" > "$criteria_file"
+  criteria_count="$(line_count "$criteria_file")"
+  if ! lint_spec_file "$spec" "$spec_text" "$criteria_count" "$strict"; then
+    printf '%s\n' "$SPEC_LINT_ERROR" >&2
+    rm -f "$criteria_file"
+    return 2
+  fi
+  rm -f "$criteria_file"
+  printf '%s\n' "$spec"
+}
+
 run_from_track() {
   local track="$1"
   local worktree spec max report_format strict coder reviewer create_pr timeout_minutes old_pwd code next_pass
-  track="$(absolute_existing_file "$track")" || {
-    printf 'track not found: %s\n' "$track" >&2
-    return 2
-  }
+  track="$(validate_track_for_run "$track")" || return $?
   worktree="$(track_value "worktree" "$track")"
   spec="$(track_value "spec" "$track")"
   max="$(track_value "max" "$track")"
@@ -2683,15 +2866,6 @@ run_from_track() {
   next_pass="$(next_pass_from_track "$track")"
   if [ "$next_pass" -gt "$max" ]; then max="$next_pass"; fi
 
-  if [ ! -d "$worktree" ]; then
-    printf 'worktree not found: %s\n' "$worktree" >&2
-    return 2
-  fi
-  if [ ! -f "$spec" ]; then
-    printf 'spec not found: %s\n' "$spec" >&2
-    return 2
-  fi
-
   old_pwd="$PWD"
   cd "$worktree" || return 2
   RUN_START_PASS="$next_pass"
@@ -2745,6 +2919,7 @@ will_enter_worktree_shell() {
 }
 
 run_command() {
+  local original_args=("$@")
   local report_format="html"
   local strict=true
   local use_worktree=true
@@ -2755,6 +2930,7 @@ run_command() {
   local spec=""
   local max_raw="5"
   local max_set=false
+  local no_tmux=false
   local arg value
   coder="$(devloop_coder)"
   reviewer="$(devloop_reviewer)"
@@ -2798,6 +2974,7 @@ run_command() {
         ;;
       --html) report_format="html" ;;
       --markdown|--md) report_format="markdown" ;;
+      --no-tmux) no_tmux=true ;;
       --no-strict) strict=false ;;
       --strict) strict=true ;;
       --in-place) use_worktree=false ;;
@@ -2836,6 +3013,17 @@ run_command() {
   if [ "$max" -lt 1 ]; then max=1; fi
   if [ "$max" -gt 10 ]; then max=10; fi
 
+  if [ "$no_tmux" = false ] && devloop_tmux_interactive; then
+    local validated_spec repo
+    validated_spec="$(validate_spec_for_tmux "$spec" "$strict")" || return $?
+    repo="$(git -C "$PWD" rev-parse --show-toplevel 2>/dev/null)" || {
+      printf '%s\n' "not inside a git repository" >&2
+      return 2
+    }
+    tmux_launch_session "$repo" "$validated_spec" run "${original_args[@]}"
+    return $?
+  fi
+
   run_header "$spec" "$max" "$report_format" "$strict" "$use_worktree" "$coder" "$reviewer" "$create_pr" "$timeout_minutes"
   run_devloop "$spec" "$max" "$report_format" "$strict" "$use_worktree" "$coder" "$reviewer" "$create_pr" "$timeout_minutes"
   local code=$?
diff --git a/scripts/devloop_test.sh b/scripts/devloop_test.sh
index 982c0ee..99e380f 100755
--- a/scripts/devloop_test.sh
+++ b/scripts/devloop_test.sh
@@ -85,6 +85,10 @@ contains "$help" "--version" "help"
 contains "$help" "--timeout-minutes" "help"
 contains "$help" "--report-format html|markdown" "help"
 contains "$help" "choose report format" "help"
+contains "$help" "named tmux session" "help"
+contains "$help" "--no-tmux" "help"
+contains "$help" "Ctrl-b d" "help"
+contains "$help" "tmux attach -t" "help"
 ok "help output"
 
 remote_help="$("$REMOTE_INSTALLER" --help)"
@@ -109,6 +113,13 @@ not_contains "$readme_text" "render.py" "README Python spec renderer"
 contains "$readme_text" "render.sh" "README spec renderer"
 contains "$readme_text" "sibling HTML companion" "README spec renderer"
 contains "$readme_text" "HTML report" "README report docs"
+contains "$readme_text" "tmux" "README required dependency"
+contains "$readme_text" "--no-tmux" "README foreground override"
+contains "$readme_text" "Ctrl-b d" "README detach guidance"
+contains "$readme_text" "tmux attach -t" "README reattach guidance"
+contributing_text="$(cat "$REPO_ROOT/CONTRIBUTING.md")"
+contains "$contributing_text" "tmux" "CONTRIBUTING required dependency"
+contains "$contributing_text" "--no-tmux" "CONTRIBUTING foreground override"
 ok "README install docs"
 
 skill_path="$("$REPO_ROOT/devloop" spec --skill-path)"
@@ -449,10 +460,313 @@ USE_TUI=true
 tui_help="$(welcome_tui)"
 contains "$tui_help" "devloop update" "TUI help"
 contains "$tui_help" "devloop nightshift" "TUI help"
+contains "$tui_help" "named tmux session" "TUI help"
+contains "$tui_help" "--no-tmux" "TUI help"
+contains "$tui_help" "Ctrl-b d" "TUI help"
+contains "$tui_help" "tmux attach -t" "TUI help"
 not_contains "$tui_help" "devloop $obsolete_update_command" "TUI help"
 USE_TUI="$old_use_tui"
 unset -f gum
 
+tmux_repo="$work/Fancy Repo!"
+mkdir -p "$tmux_repo"
+tmux_repo="$(cd "$tmux_repo" >/dev/null 2>&1 && pwd -P)"
+tmux_spec="$tmux_repo/Spec @ One.md"
+tmux_track="$tmux_repo/continued-run.md"
+git init -q "$tmux_repo"
+cat > "$tmux_spec" <<'TMUX_SPEC'
+---
+type: feat
+---
+
+# Tmux Spec
+
+## Acceptance criteria
+1. Exercise the tmux boundary.
+TMUX_SPEC
+cat > "$tmux_track" <<TRACK
+# Track
+
+- spec: $tmux_spec
+- source-repo: $tmux_repo
+- worktree: $tmux_repo
+TRACK
+
+equals "$(tmux_normalize_component " Fancy !! Name " repo)" "fancy-name" "tmux component normalization"
+equals "$(tmux_normalize_component "!!!" repo)" "repo" "tmux component fallback"
+equals "$(tmux_session_base_name "$tmux_repo" "$tmux_spec")" "devloop-fancy-repo-spec-one" "tmux run session base"
+equals "$(tmux_session_base_name "$work/!!!" "$work/---.md")" "devloop-repo-run" "tmux session fallback base"
+if devloop_tmux_interactive </dev/null; then fail "tmux eligibility accepted non-TTY stdin"; fi
+if (devloop_tmux_interactive) > "$work/non-tty-stdout"; then fail "tmux eligibility accepted non-TTY stdout"; fi
+
+tmux_bin="$work/tmux-bin"
+tmux_log="$work/tmux.log"
+mkdir -p "$tmux_bin"
+cat > "$tmux_bin/tmux" <<'TMUX'
+#!/usr/bin/env bash
+set -euo pipefail
+{
+  printf '%s\n' "CALL"
+  for arg in "$@"; do printf 'ARG=%s\n' "$arg"; done
+  printf '%s\n' "END"
+} >> "$DEVLOOP_TMUX_LOG"
+case "${1:-}" in
+  list-sessions)
+    if [ -n "${DEVLOOP_TMUX_SESSIONS:-}" ]; then printf '%s\n' "$DEVLOOP_TMUX_SESSIONS"; fi
+    ;;
+  new-session)
+    if [ "${DEVLOOP_TMUX_NEW_FAIL:-0}" = "1" ]; then exit 17; fi
+    ;;
+  switch-client)
+    if [ "${DEVLOOP_TMUX_SWITCH_FAIL:-0}" = "1" ]; then exit 19; fi
+    ;;
+esac
+TMUX
+chmod +x "$tmux_bin/tmux"
+old_path="$PATH"
+PATH="$tmux_bin:$PATH"
+DEVLOOP_TMUX_LOG="$tmux_log"
+export PATH DEVLOOP_TMUX_LOG
+
+: > "$tmux_log"
+DEVLOOP_TMUX_SESSIONS=$'devloop-fancy-repo-spec-one\ndevloop-fancy-repo-spec-one-2'
+export DEVLOOP_TMUX_SESSIONS
+equals "$(tmux_allocate_session_name "devloop-fancy-repo-spec-one")" "devloop-fancy-repo-spec-one-3" "tmux collision allocation"
+contains "$(cat "$tmux_log")" "ARG=#{session_name}" "tmux exact session listing"
+
+: > "$tmux_log"
+DEVLOOP_TMUX_SESSIONS=""
+export DEVLOOP_TMUX_SESSIONS
+tmux_marker="$work/tmux-shell-interpolation-marker"
+if ! (
+  cd "$tmux_repo"
+  unset TMUX
+  tmux_launch_session "$tmux_repo" "$tmux_spec" run --plain "arg with spaces" "; touch $tmux_marker"
+); then
+  fail "outside-tmux launch failed"
+fi
+outside_tmux_log="$(cat "$tmux_log")"
+contains "$outside_tmux_log" "ARG=new-session" "outside-tmux launch"
+contains "$outside_tmux_log" "ARG=-s" "outside-tmux named session"
+contains "$outside_tmux_log" "ARG=devloop-fancy-repo-spec-one" "outside-tmux session name"
+contains "$outside_tmux_log" "ARG=-c" "outside-tmux working directory flag"
+contains "$outside_tmux_log" "ARG=$tmux_repo" "outside-tmux working directory"
+contains "$outside_tmux_log" "ARG=PATH=$PATH" "outside-tmux PATH forwarding"
+contains "$outside_tmux_log" "ARG=$SCRIPT_PATH" "outside-tmux runtime"
+contains "$outside_tmux_log" "ARG=arg with spaces" "outside-tmux argv spaces"
+contains "$outside_tmux_log" "ARG=; touch $tmux_marker" "outside-tmux argv metacharacters"
+not_contains "$outside_tmux_log" "ARG=-d" "outside-tmux attached launch"
+not_contains "$outside_tmux_log" "ARG=-A" "outside-tmux never reuses a session"
+not_contains "$outside_tmux_log" "ARG=sh" "outside-tmux no shell wrapper"
+equals "$(count_occurrences "$tmux_log" "ARG=--no-tmux")" "1" "outside-tmux recursion guard"
+[[ ! -e "$tmux_marker" ]] || fail "tmux launcher evaluated a child argument"
+
+: > "$tmux_log"
+TMUX="/tmp/fake-tmux,1,0"
+export TMUX
+if ! (cd "$tmux_repo" && tmux_launch_session "$tmux_repo" "$tmux_track" continue "$tmux_track"); then
+  fail "inside-tmux launch failed"
+fi
+inside_tmux_log="$(cat "$tmux_log")"
+contains "$inside_tmux_log" "ARG=-d" "inside-tmux detached creation"
+contains "$inside_tmux_log" "ARG=switch-client" "inside-tmux client switch"
+contains "$inside_tmux_log" "ARG=continue" "inside-tmux continue command"
+equals "$(count_occurrences "$tmux_log" "ARG=--no-tmux")" "1" "inside-tmux recursion guard"
+
+: > "$tmux_log"
+DEVLOOP_TMUX_NEW_FAIL=1
+export DEVLOOP_TMUX_NEW_FAIL
+if tmux_new_failure_output="$(cd "$tmux_repo" && tmux_launch_session "$tmux_repo" "$tmux_spec" run "$tmux_spec" 2>&1)"; then
+  fail "tmux launcher accepted failed new-session"
+fi
+contains "$tmux_new_failure_output" "failed to create tmux session" "tmux new-session failure"
+not_contains "$(cat "$tmux_log")" "ARG=switch-client" "tmux new-session failure does not switch"
+unset DEVLOOP_TMUX_NEW_FAIL
+
+: > "$tmux_log"
+DEVLOOP_TMUX_SWITCH_FAIL=1
+export DEVLOOP_TMUX_SWITCH_FAIL
+if tmux_switch_failure_output="$(cd "$tmux_repo" && tmux_launch_session "$tmux_repo" "$tmux_spec" run "$tmux_spec" 2>&1)"; then
+  fail "tmux launcher accepted failed switch-client"
+fi
+contains "$tmux_switch_failure_output" "tmux session is still running" "tmux switch failure preservation"
+contains "$tmux_switch_failure_output" "tmux switch-client -t devloop-fancy-repo-spec-one" "tmux switch recovery"
+contains "$tmux_switch_failure_output" "tmux attach -t devloop-fancy-repo-spec-one" "tmux attach recovery"
+equals "$(count_occurrences "$tmux_log" "ARG=new-session")" "1" "tmux switch failure single launch"
+unset DEVLOOP_TMUX_SWITCH_FAIL TMUX
+
+if tmux_missing_output="$(
+  tmux_command_available() { return 1; }
+  tmux_launch_session "$tmux_repo" "$tmux_spec" run "$tmux_spec" 2>&1
+)"; then
+  fail "tmux launcher accepted missing tmux"
+fi
+contains "$tmux_missing_output" "rerun the installer or install tmux" "missing tmux guidance"
+ok "tmux launcher helpers"
+
+tmux_boundary_log="$work/tmux-boundary.log"
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() {
+    printf 'launch' >> "$tmux_boundary_log"
+    for arg in "$@"; do printf ' <%s>' "$arg" >> "$tmux_boundary_log"; done
+    printf '\n' >> "$tmux_boundary_log"
+  }
+  run_header() { :; }
+  run_devloop() { printf '%s\n' "unexpected foreground run" >> "$tmux_boundary_log"; }
+  maybe_enter_worktree() { :; }
+  run_command --coder claude --reviewer codex --timeout-minutes 9 "$tmux_spec" 3
+); then
+  fail "eligible explicit run failed"
+fi
+explicit_launch="$(cat "$tmux_boundary_log")"
+contains "$explicit_launch" "launch <$tmux_repo> <$tmux_spec> <run>" "eligible explicit run boundary"
+contains "$explicit_launch" "<--coder> <claude>" "eligible explicit run coder argv"
+contains "$explicit_launch" "<--reviewer> <codex>" "eligible explicit run reviewer argv"
+not_contains "$explicit_launch" "foreground" "eligible explicit run executes only in tmux"
+
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf '%s\n' "unexpected tmux launch" >> "$tmux_boundary_log"; return 99; }
+  run_header() { :; }
+  run_devloop() { printf 'foreground'; for arg in "$@"; do printf ' <%s>' "$arg"; done; printf '\n'; }
+  maybe_enter_worktree() { :; }
+  run_command --no-tmux --plain "$tmux_spec" 2 > "$tmux_boundary_log"
+); then
+  fail "--no-tmux explicit run failed"
+fi
+contains "$(cat "$tmux_boundary_log")" "foreground <$tmux_spec> <2>" "--no-tmux explicit foreground run"
+not_contains "$(cat "$tmux_boundary_log")" "unexpected tmux" "--no-tmux explicit run bypass"
+
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 1; }
+  tmux_launch_session() { printf '%s\n' "unexpected tmux launch" >> "$tmux_boundary_log"; return 99; }
+  run_header() { :; }
+  run_devloop() { printf '%s\n' "foreground noninteractive"; }
+  maybe_enter_worktree() { :; }
+  run_command "$tmux_spec" > "$tmux_boundary_log"
+); then
+  fail "noninteractive explicit run failed"
+fi
+equals "$(cat "$tmux_boundary_log")" "foreground noninteractive" "noninteractive explicit foreground run"
+
+: > "$tmux_boundary_log"
+if (
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf '%s\n' "launch attempted" >> "$tmux_boundary_log"; return 17; }
+  run_header() { :; }
+  run_devloop() { printf '%s\n' "foreground retry" >> "$tmux_boundary_log"; }
+  run_command "$tmux_spec"
+); then
+  fail "explicit run accepted tmux launch failure"
+fi
+equals "$(cat "$tmux_boundary_log")" "launch attempted" "tmux failure has no foreground retry"
+
+: > "$tmux_boundary_log"
+if invalid_spec_output="$(
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf '%s\n' "launch attempted" >> "$tmux_boundary_log"; }
+  run_command "$tmux_repo/missing.md" 2>&1
+)"; then
+  fail "explicit run accepted missing spec"
+fi
+contains "$invalid_spec_output" "usage: devloop" "missing spec validation"
+[[ ! -s "$tmux_boundary_log" ]] || fail "missing spec created a tmux session"
+
+equals "$(validate_track_for_run "$tmux_track")" "$tmux_track" "continue track validation"
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf 'launch'; for arg in "$@"; do printf ' <%s>' "$arg"; done; printf '\n'; }
+  run_from_track() { printf '%s\n' "unexpected foreground continue"; }
+  continue_command "$tmux_track" > "$tmux_boundary_log"
+); then
+  fail "eligible explicit continue failed"
+fi
+contains "$(cat "$tmux_boundary_log")" "launch <$tmux_repo> <$tmux_track> <continue> <$tmux_track>" "eligible explicit continue boundary"
+not_contains "$(cat "$tmux_boundary_log")" "foreground" "eligible explicit continue executes only in tmux"
+
+: > "$tmux_boundary_log"
+if ! (
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf '%s\n' "unexpected tmux launch"; return 99; }
+  run_from_track() { printf 'foreground continue <%s>\n' "$1"; }
+  continue_command --no-tmux "$tmux_track" > "$tmux_boundary_log"
+); then
+  fail "--no-tmux explicit continue failed"
+fi
+equals "$(cat "$tmux_boundary_log")" "foreground continue <$tmux_track>" "--no-tmux continue foreground"
+
+: > "$tmux_boundary_log"
+if invalid_track_output="$(
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf '%s\n' "launch attempted" >> "$tmux_boundary_log"; }
+  continue_command "$tmux_repo/missing-track.md" 2>&1
+)"; then
+  fail "continue accepted missing track"
+fi
+contains "$invalid_track_output" "track not found" "missing track validation"
+[[ ! -s "$tmux_boundary_log" ]] || fail "missing track created a tmux session"
+
+menu_prompt_log="$work/menu-prompt.log"
+: > "$menu_prompt_log"
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  USE_TUI=true
+  ENTER_WORKTREE=false
+  UI_BACK=false
+  devloop_tmux_interactive() { return 0; }
+  devloop_coder() { printf '%s\n' "claude"; }
+  devloop_reviewer() { printf '%s\n' "codex"; }
+  devloop_timeout_minutes() { printf '%s\n' "42"; }
+  interactive_create_pr_choice() { printf '%s\n' "prompt" >> "$menu_prompt_log"; printf '%s\n' "true"; }
+  run_header() { :; }
+  tmux_launch_session() { printf 'launch'; for arg in "$@"; do printf ' <%s>' "$arg"; done; printf '\n'; }
+  run_devloop() { printf '%s\n' "unexpected foreground menu run"; }
+  interactive_run_setup "$tmux_spec" > "$tmux_boundary_log"
+); then
+  fail "menu-selected tmux run failed"
+fi
+menu_launch="$(cat "$tmux_boundary_log")"
+contains "$menu_launch" "launch <$tmux_repo> <$tmux_spec> <run>" "menu-selected run boundary"
+contains "$menu_launch" "<--tui>" "menu-selected run TUI choice"
+contains "$menu_launch" "<--coder> <claude>" "menu-selected run coder choice"
+contains "$menu_launch" "<--reviewer> <codex>" "menu-selected run reviewer choice"
+contains "$menu_launch" "<--timeout-minutes> <42>" "menu-selected run timeout choice"
+contains "$menu_launch" "<--create-pr>" "menu-selected run PR choice"
+contains "$menu_launch" "<--no-shell>" "menu-selected run shell choice"
+equals "$(wc -l < "$menu_prompt_log" | tr -d ' ')" "1" "menu-selected run prompts once before tmux"
+
+: > "$tmux_boundary_log"
+if ! (
+  cd "$tmux_repo"
+  UI_BACK=false
+  list_artifact_files() { printf '%s\n' "$tmux_track"; }
+  ui_pick_from_file() { sed -n '1p' "$1"; }
+  devloop_tmux_interactive() { return 0; }
+  tmux_launch_session() { printf 'launch'; for arg in "$@"; do printf ' <%s>' "$arg"; done; printf '\n'; }
+  run_from_track() { printf '%s\n' "unexpected foreground menu continue"; }
+  interactive_continue_run > "$tmux_boundary_log"
+); then
+  fail "menu-selected tmux continue failed"
+fi
+equals "$(cat "$tmux_boundary_log")" "launch <$tmux_repo> <$tmux_track> <continue> <$tmux_track>" "menu-selected continue boundary"
+ok "tmux run and continue boundaries"
+
+PATH="$old_path"
+export PATH
+unset DEVLOOP_TMUX_LOG DEVLOOP_TMUX_SESSIONS
+
 criteria_file="$work/criteria.md"
 cat > "$criteria_file" <<'MARKDOWN'
 # Spec
@@ -1032,7 +1346,7 @@ night_digest="$night_repo_real/.devloop/nightshift/2026-07-05/digest.md"
 contains "$(cat "$night_prompt_capture")" "write specs only, do not implement" "nightshift survey prompt capture"
 contains "$(cat "$night_survey_args_capture")" "$night_repo_real|nightshift-survey|claude -p" "nightshift survey uses run_with_prompt"
 equals "$(grep -c '^args ' "$night_run_log" | tr -d ' ')" "5" "nightshift runner invocation count"
-contains "$(cat "$night_run_log")" "--plain --no-shell --create-pr --coder claude --reviewer codex --timeout-minutes 12" "nightshift runner headless flags"
+contains "$(cat "$night_run_log")" "--plain --no-tmux --no-shell --create-pr --coder claude --reviewer codex --timeout-minutes 12" "nightshift runner headless flags"
 contains "$(cat "$night_run_log")" "$night_repo_real/.devloop/nightshift/2026-07-05/specs/01-first.md 4" "nightshift runner max passes"
 equals "$(grep -E '^(start|end) ' "$night_run_log")" $'start 01-first.md\nend 01-first.md\nstart 02-second.md\nend 02-second.md\nstart 03-third.md\nend 03-third.md\nstart 04-timeout.md\nend 04-timeout.md\nstart 05-crash.md\nend 05-crash.md' "nightshift runner sequential order"
 equals "$(cat "$night_leak_capture")" "global-branch|global-pr|global-report" "nightshift run repo local scoping"
@@ -1578,7 +1892,21 @@ make_remote_release "$remote_version" "$remote_releases"
 remote_release_base="file://$remote_releases"
 remote_no_tools="$work/remote-no-tools"
 mkdir -p "$remote_no_tools"
-remote_no_tools_path="$remote_no_tools:/usr/bin:/bin:/usr/sbin:/sbin"
+for remote_system_dir in /usr/bin /bin /usr/sbin /sbin; do
+  [ -d "$remote_system_dir" ] || continue
+  for remote_system_entry in "$remote_system_dir"/*; do
+    remote_system_name="$(basename "$remote_system_entry")"
+    case "$remote_system_name" in
+      brew|claude|codex|fzf|gh|glow|gum|tmux) continue ;;
+    esac
+    [ -e "$remote_no_tools/$remote_system_name" ] && continue
+    ln -s "$remote_system_entry" "$remote_no_tools/$remote_system_name"
+  done
+done
+remote_no_tools_path="$remote_no_tools"
+if PATH="$remote_no_tools_path" command -v tmux >/dev/null 2>&1; then
+  fail "remote no-tools fixture exposed tmux"
+fi
 
 remote_custom_root="$work/remote-custom-root"
 remote_custom_bin="$work/remote-custom-bin"
@@ -1598,8 +1926,8 @@ contains "$remote_dry_output" "verify: $remote_release_base/v$remote_version/dev
 contains "$remote_dry_output" "install: $remote_custom_root/$remote_version" "remote dry run install dir"
 contains "$remote_dry_output" "link: $remote_custom_bin/devloop -> $remote_custom_root/$remote_version/devloop" "remote dry run bin dir"
 contains "$remote_dry_output" "skills: $work/remote-dry-home/.agents/skills, $work/remote-dry-home/.claude/skills" "remote dry run skills"
-contains "$remote_dry_output" "missing required dependencies: glow gum fzf" "remote missing UI guidance"
-contains "$remote_dry_output" "install with: brew install glow gum fzf" "remote missing UI guidance"
+contains "$remote_dry_output" "missing required dependencies: glow gum fzf tmux" "remote missing UI guidance"
+contains "$remote_dry_output" "install with: brew install glow gum fzf tmux" "remote missing UI guidance"
 contains "$remote_dry_output" "missing required cask dependencies: codex claude-code" "remote missing agent guidance"
 contains "$remote_dry_output" "install with: brew install --cask codex claude-code" "remote missing agent guidance"
 [[ ! -e "$remote_custom_root" ]] || fail "remote dry run created install root"
@@ -1666,7 +1994,7 @@ remote_needs_yes_bin="$work/remote-needs-yes-bin"
 mkdir -p "$remote_needs_yes_bin"
 printf '%s\n' '#!/usr/bin/env bash' 'exit 0' > "$remote_needs_yes_bin/brew"
 chmod +x "$remote_needs_yes_bin/brew"
-remote_needs_yes_path="$remote_needs_yes_bin:/usr/bin:/bin:/usr/sbin:/sbin"
+remote_needs_yes_path="$remote_needs_yes_bin:$remote_no_tools_path"
 if remote_needs_yes_output="$(
   HOME="$work/remote-needs-yes-home" PATH="$remote_needs_yes_path" bash "$REMOTE_INSTALLER" \
     --version "$remote_version" \
@@ -1684,7 +2012,7 @@ remote_noop_brew_bin="$work/remote-noop-brew-bin"
 mkdir -p "$remote_noop_brew_bin"
 printf '%s\n' '#!/usr/bin/env bash' 'exit 0' > "$remote_noop_brew_bin/brew"
 chmod +x "$remote_noop_brew_bin/brew"
-remote_noop_brew_path="$remote_noop_brew_bin:/usr/bin:/bin:/usr/sbin:/sbin"
+remote_noop_brew_path="$remote_noop_brew_bin:$remote_no_tools_path"
 if remote_noop_brew_output="$(
   HOME="$work/remote-noop-brew-home" PATH="$remote_noop_brew_path" bash "$REMOTE_INSTALLER" \
     --yes \
@@ -1700,11 +2028,11 @@ ok "remote installer fails when dependencies remain missing"
 
 remote_tool_bin="$work/remote-tool-bin"
 mkdir -p "$remote_tool_bin"
-for tool in glow gum fzf codex claude; do
+for tool in glow gum fzf tmux codex claude; do
   printf '%s\n' '#!/usr/bin/env bash' 'exit 0' > "$remote_tool_bin/$tool"
   chmod +x "$remote_tool_bin/$tool"
 done
-remote_path="$remote_tool_bin:/usr/bin:/bin:/usr/sbin:/sbin"
+remote_path="$remote_tool_bin:$remote_no_tools_path"
 
 update_root="$work/update-root"
 update_bin="$work/update-bin"
@@ -1858,7 +2186,7 @@ if [ "${1:-}" = "--cask" ]; then shift; fi
 tool_dir="$(cd "$(dirname "$0")" >/dev/null 2>&1 && pwd)"
 for formula in "$@"; do
   case "$formula" in
-    git|glow|gum|fzf|codex)
+    git|glow|gum|fzf|tmux|codex)
       command_name="$formula"
       printf '%s\n' '#!/usr/bin/env bash' 'exit 0' > "$tool_dir/$command_name"
       chmod +x "$tool_dir/$command_name"
@@ -1873,7 +2201,7 @@ done
 BREW
 chmod +x "$remote_bootstrap_bin/brew"
 remote_bootstrap_home="$work/remote-bootstrap-home"
-remote_bootstrap_path="$remote_bootstrap_bin:/usr/bin:/bin:/usr/sbin:/sbin"
+remote_bootstrap_path="$remote_bootstrap_bin:$remote_no_tools_path"
 if ! remote_bootstrap_output="$(
   HOME="$remote_bootstrap_home" PATH="$remote_bootstrap_path" bash "$REMOTE_INSTALLER" \
     --yes \
@@ -1884,11 +2212,12 @@ if ! remote_bootstrap_output="$(
   printf '%s\n' "$remote_bootstrap_output" >&2
   fail "remote installer dependency bootstrap failed"
 fi
-contains "$remote_bootstrap_output" "installing required dependencies: glow gum fzf" "remote installer installs UI dependencies"
+contains "$remote_bootstrap_output" "installing required dependencies: glow gum fzf tmux" "remote installer installs UI dependencies"
 contains "$remote_bootstrap_output" "installing required cask dependencies: codex claude-code" "remote installer installs agent dependencies"
 PATH="$remote_bootstrap_path" command -v glow >/dev/null 2>&1 || fail "remote installer did not make glow available"
 PATH="$remote_bootstrap_path" command -v gum >/dev/null 2>&1 || fail "remote installer did not make gum available"
 PATH="$remote_bootstrap_path" command -v fzf >/dev/null 2>&1 || fail "remote installer did not make fzf available"
+PATH="$remote_bootstrap_path" command -v tmux >/dev/null 2>&1 || fail "remote installer did not make tmux available"
 PATH="$remote_bootstrap_path" command -v codex >/dev/null 2>&1 || fail "remote installer did not make codex available"
 PATH="$remote_bootstrap_path" command -v claude >/dev/null 2>&1 || fail "remote installer did not make claude available"
 ok "remote installer bootstraps missing dependencies"
@@ -2014,7 +2343,7 @@ if [ "${1:-}" = "--cask" ]; then shift; fi
 tool_dir="$(cd "$(dirname "$0")" >/dev/null 2>&1 && pwd)"
 for formula in "$@"; do
   case "$formula" in
-    git|glow|gum|fzf|codex)
+    git|glow|gum|fzf|tmux|codex)
       command_name="$formula"
       printf '%s\n' '#!/usr/bin/env bash' 'exit 0' > "$tool_dir/$command_name"
       chmod +x "$tool_dir/$command_name"
@@ -2036,6 +2365,7 @@ contains "$(cat /tmp/devloop-install-test.out)" "gh auth login" "installer optio
 PATH="$install_path" command -v glow >/dev/null 2>&1 || fail "installer did not make glow available"
 PATH="$install_path" command -v gum >/dev/null 2>&1 || fail "installer did not make gum available"
 PATH="$install_path" command -v fzf >/dev/null 2>&1 || fail "installer did not make fzf available"
+PATH="$install_path" command -v tmux >/dev/null 2>&1 || fail "installer did not make tmux available"
 PATH="$install_path" command -v codex >/dev/null 2>&1 || fail "installer did not make codex available"
 PATH="$install_path" command -v claude >/dev/null 2>&1 || fail "installer did not make claude available"
 [[ -f "$install_home/.agents/skills/devloop-spec/SKILL.md" ]] || fail "installer did not install Codex spec skill"
@@ -2232,6 +2562,7 @@ contains "$doctor_output" "[ok] glow:" "doctor"
 contains "$doctor_output" "[ok] skill devloop-spec" "doctor"
 contains "$doctor_output" "[ok] gum:" "doctor"
 contains "$doctor_output" "[ok] fzf:" "doctor"
+contains "$doctor_output" "[ok] tmux:" "doctor"
 contains "$doctor_output" "GitHub PR integration" "doctor"
 contains "$doctor_output" "[PASS] gh installed" "doctor"
 contains "$doctor_output" "[PASS] gh authenticated" "doctor"
@@ -2244,24 +2575,15 @@ ok "doctor"
 
 no_gh_bin="$work/no-gh-bin"
 mkdir -p "$no_gh_bin"
-printf '#!/usr/bin/env bash\nexit 0\n' > "$no_gh_bin/codex"
-printf '#!/usr/bin/env bash\nexit 0\n' > "$no_gh_bin/claude"
-printf '#!/usr/bin/env bash\nexit 0\n' > "$no_gh_bin/glow"
-chmod +x "$no_gh_bin/codex" "$no_gh_bin/claude" "$no_gh_bin/glow"
-# Mirror the system bin dirs without gh so `command -v gh` fails regardless of
-# where gh is installed on the host (CI runners ship gh in /usr/bin).
-sys_clean="$work/sys-clean"
-mkdir -p "$sys_clean"
-for sys_dir in /usr/bin /bin; do
-  [ -d "$sys_dir" ] || continue
-  for sys_entry in "$sys_dir"/*; do
-    sys_name="$(basename "$sys_entry")"
-    [ "$sys_name" = "gh" ] && continue
-    [ -e "$sys_clean/$sys_name" ] && continue
-    ln -s "$sys_entry" "$sys_clean/$sys_name"
-  done
+for tool in codex claude glow gum fzf tmux; do
+  printf '#!/usr/bin/env bash\nexit 0\n' > "$no_gh_bin/$tool"
+  chmod +x "$no_gh_bin/$tool"
 done
-doctor_no_gh_output="$(HOME="$install_home" PATH="$bin_dir:$tool_bin:$no_gh_bin:$sys_clean" "$bin_dir/devloop" doctor 2>&1)" || fail "doctor failed when gh was unavailable"
+sys_clean="$remote_no_tools"
+if ! doctor_no_gh_output="$(HOME="$install_home" PATH="$bin_dir:$no_gh_bin:$sys_clean" "$bin_dir/devloop" doctor 2>&1)"; then
+  printf '%s\n' "$doctor_no_gh_output" >&2
+  fail "doctor failed when gh was unavailable"
+fi
 contains "$doctor_no_gh_output" "devloop doctor: ready" "doctor no gh"
 contains "$doctor_no_gh_output" "[FAIL] gh installed" "doctor no gh"
 contains "$doctor_no_gh_output" "PR-backed loop readiness unavailable" "doctor no gh"
@@ -2273,7 +2595,8 @@ printf '#!/usr/bin/env bash\nexit 0\n' > "$no_glow_bin/codex"
 printf '#!/usr/bin/env bash\nexit 0\n' > "$no_glow_bin/claude"
 printf '#!/usr/bin/env bash\nexit 0\n' > "$no_glow_bin/gum"
 printf '#!/usr/bin/env bash\nexit 0\n' > "$no_glow_bin/fzf"
-chmod +x "$no_glow_bin/codex" "$no_glow_bin/claude" "$no_glow_bin/gum" "$no_glow_bin/fzf"
+printf '#!/usr/bin/env bash\nexit 0\n' > "$no_glow_bin/tmux"
+chmod +x "$no_glow_bin/codex" "$no_glow_bin/claude" "$no_glow_bin/gum" "$no_glow_bin/fzf" "$no_glow_bin/tmux"
 if doctor_no_glow_output="$(HOME="$install_home" PATH="$bin_dir:$no_glow_bin:$sys_clean" "$bin_dir/devloop" doctor 2>&1)"; then
   printf '%s\n' "$doctor_no_glow_output" >&2
   fail "doctor passed when glow was unavailable"
@@ -2282,6 +2605,20 @@ contains "$doctor_no_glow_output" "[fail] missing command: glow" "doctor no glow
 contains "$doctor_no_glow_output" "devloop doctor: not ready" "doctor no glow"
 ok "doctor requires glow"
 
+no_tmux_bin="$work/no-tmux-bin"
+mkdir -p "$no_tmux_bin"
+for tool in codex claude glow gum fzf; do
+  printf '#!/usr/bin/env bash\nexit 0\n' > "$no_tmux_bin/$tool"
+  chmod +x "$no_tmux_bin/$tool"
+done
+if doctor_no_tmux_output="$(HOME="$install_home" PATH="$bin_dir:$no_tmux_bin:$sys_clean" "$bin_dir/devloop" doctor 2>&1)"; then
+  printf '%s\n' "$doctor_no_tmux_output" >&2
+  fail "doctor passed when tmux was unavailable"
+fi
+contains "$doctor_no_tmux_output" "[fail] missing command: tmux" "doctor no tmux"
+contains "$doctor_no_tmux_output" "devloop doctor: not ready" "doctor no tmux"
+ok "doctor requires tmux"
+
 agent="$work/spec-agent"
 cat > "$agent" <<'AGENT'
 #!/usr/bin/env bash
@@ -2450,7 +2787,7 @@ contains "$(HOME="$helper_home" devloop_skills_dirs)" "$helper_home/.agents/skil
 devloop_can_replace_skill "$helper_home/.agents/skills/devloop-spec" || fail "installed skill should be replaceable"
 devloop_valid_skill_name "devloop-spec" || fail "valid skill name rejected"
 equals "$(devloop_skill_name "$helper_home/.agents/skills/devloop-spec/SKILL.md")" "devloop-spec" "skill name"
-helper_doctor_output="$(HOME="$helper_home" PATH="$fake_bin:$bin_dir:$tool_bin:$sys_clean" devloop_doctor "$REPO_ROOT" 2>&1)" || fail "direct doctor failed"
+helper_doctor_output="$(HOME="$helper_home" PATH="$fake_bin:$bin_dir:$no_gh_bin:$sys_clean" devloop_doctor "$REPO_ROOT" 2>&1)" || fail "direct doctor failed"
 contains "$helper_doctor_output" "devloop doctor: ready" "direct doctor"
 ok "direct skill helpers"
 
diff --git a/scripts/install.remote.sh b/scripts/install.remote.sh
index ce5d21e..afc4e8f 100755
--- a/scripts/install.remote.sh
+++ b/scripts/install.remote.sh
@@ -217,7 +217,7 @@ missing_agent_casks() {
 
 print_dependency_status() {
   local tool
-  for tool in git glow gum fzf codex claude; do
+  for tool in git glow gum fzf tmux codex claude; do
     if command -v "$tool" >/dev/null 2>&1; then
       info "[ok] $tool: $(command -v "$tool")"
     fi
@@ -305,7 +305,7 @@ install_required_dependencies() {
     brew install --cask "${missing_casks[@]}"
   fi
 
-  still_missing="$(missing_commands git glow gum fzf codex claude)"
+  still_missing="$(missing_commands git glow gum fzf tmux codex claude)"
   if [ -n "$still_missing" ]; then
     info "still missing required dependencies: $still_missing"
     return 1
@@ -410,7 +410,7 @@ main() {
     VERSION="$(resolve_latest_version)"
   fi
   version="$(normalize_version "$VERSION")"
-  formula_missing="$(missing_commands git glow gum fzf)"
+  formula_missing="$(missing_commands git glow gum fzf tmux)"
   cask_missing="$(missing_agent_casks)"
 
   if [ "$DRY_RUN" = true ]; then
diff --git a/scripts/install.sh b/scripts/install.sh
index 9fb58fa..e393060 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -52,7 +52,7 @@ install_required_dependencies() {
   local missing_text
   local tool
 
-  for tool in git glow gum fzf; do
+  for tool in git glow gum fzf tmux; do
     if ! command -v "$tool" >/dev/null 2>&1; then
       missing_formulas+=("$tool")
     fi
@@ -92,7 +92,7 @@ install_required_dependencies() {
     brew install --cask "${missing_casks[@]}"
   fi
 
-  for tool in git glow gum fzf codex claude; do
+  for tool in git glow gum fzf tmux codex claude; do
     if ! command -v "$tool" >/dev/null 2>&1; then
       echo "failed to install required dependency: $tool" >&2
       return 1
diff --git a/scripts/skill_helpers.sh b/scripts/skill_helpers.sh
index f5fcdaa..da3627e 100644
--- a/scripts/skill_helpers.sh
+++ b/scripts/skill_helpers.sh
@@ -353,6 +353,7 @@ devloop_doctor() {
   devloop_doctor_command glow || status=1
   devloop_doctor_command gum || status=1
   devloop_doctor_command fzf || status=1
+  devloop_doctor_command tmux || status=1
   printf '\nSkills\n'
   devloop_doctor_skills "$root" || status=1
   devloop_doctor_github