diff --git a/bin/omarchy-agent b/bin/omarchy-agent
index 426ea85a..05f1e1a1 100755
--- a/bin/omarchy-agent
+++ b/bin/omarchy-agent
@@ -87,10 +87,8 @@ codex)
   [[ -n ${prompt:-} ]] && command+=(-- "$prompt")
   ;;
 hermes)
-  # Hermes has no "start interactive, seeded with this prompt" mode. --oneshot
-  # answers the prompt and exits, which is the closest it offers.
   if [[ -n ${prompt:-} ]]; then
-    command=(hermes --yolo --oneshot "$prompt")
+    command=(env -u HERMES_SESSION_SOURCE hermes chat --yolo --tui "--query=$prompt")
   else
     command=(hermes --yolo)
   fi
diff --git a/bin/omarchy-install-hermes-cli b/bin/omarchy-install-hermes-cli
index 0c2e526e..5b6a3598 100755
--- a/bin/omarchy-install-hermes-cli
+++ b/bin/omarchy-install-hermes-cli
@@ -55,7 +55,7 @@ desktop_hermes_ready() {
 
   # And a marker left behind by an install whose venv has since gone answers
   # for nothing, so the command has to run, exactly as a foreign one must.
-  hermes_runs
+  hermes_prompt_ready
 }
 
 # Whether Hermes is really installed, not merely whether the stub exists. A
@@ -88,6 +88,15 @@ hermes_runs() {
     timeout 15 "$HOME/.local/bin/hermes" --version >/dev/null 2>&1
 }
 
+# The chat subcommand's --oneshot opt-out arrived with native interactive -q,
+# so its presence is a stable capability check without relying on a version.
+hermes_prompt_ready() {
+  local help
+  hermes_runs &&
+    help=$(timeout 15 "$HOME/.local/bin/hermes" chat --help 2>/dev/null) &&
+    grep -qF -- '--oneshot' <<<"$help"
+}
+
 # --owns answers whether the wrapper on PATH is the one this command wrote, so
 # the migration and Remove Preinstalls do not each carry their own copy of the
 # marker and drift from it.
@@ -101,12 +110,12 @@ if [[ $mode == "--check" ]]; then
   if desktop_owns_hermes; then
     if desktop_hermes_ready; then exit 0; else exit 1; fi
   fi
-  # A foreign command is ready when it runs; a broken one is not, and since it
-  # is not ours to replace, nothing this installer does will make it ready.
+  # A foreign command is ready only when it also supports prompted sessions;
+  # since it is not ours to replace, nothing this installer does will update it.
   if foreign_hermes; then
-    if hermes_runs; then exit 0; else exit 1; fi
+    if hermes_prompt_ready; then exit 0; else exit 1; fi
   fi
-  if installed; then exit 0; else exit 1; fi
+  if installed && hermes_prompt_ready; then exit 0; else exit 1; fi
 fi
 
 # Hand Hermes over to the app rather than keeping a second copy beside it.
@@ -140,15 +149,34 @@ fi
 # The user already has a hermes of their own. Leave it be: a working one is
 # what the default agent will run, and a broken one is theirs to fix.
 if foreign_hermes; then
-  if hermes_runs; then
+  if hermes_prompt_ready; then
     exit 0
   fi
 
+  if hermes_runs; then
+    echo "~/.local/bin/hermes does not support the interactive seeded sessions Omarchy needs." >&2
+    echo "Update it to a Hermes Agent release with interactive chat queries, then run omarchy-install-hermes-cli again." >&2
+    exit 1
+  fi
+
   echo "~/.local/bin/hermes exists but is not runnable, and it was not installed by Omarchy." >&2
   echo "Fix or remove it, then run omarchy-install-hermes-cli again." >&2
   exit 1
 fi
 
+# Only the marked wrapper proves the matching mise environment is ours to replace.
+if installed && ! hermes_prompt_ready; then
+  if ours; then
+    echo "Updating Hermes for prompted sessions..." >&2
+    mise rm -g "$tool" >/dev/null 2>&1 || true
+    mise uninstall --all "$tool" >/dev/null 2>&1 || true
+  else
+    echo "A Hermes mise environment exists without an Omarchy-owned wrapper." >&2
+    echo "Update or remove it explicitly, then run omarchy-install-hermes-cli again." >&2
+    exit 1
+  fi
+fi
+
 mkdir -p "$HOME/.local/bin"
 rm -f "$HOME/.local/bin/hermes"
 
@@ -194,4 +222,8 @@ chmod +x "$HOME/.local/bin/hermes"
 # hands Hermes to the GUI has to install it here rather than leave it stubbed.
 if [[ $mode == "--now" ]]; then
   "$HOME/.local/bin/hermes" --version
+  if ! hermes_prompt_ready; then
+    echo "Hermes installed without the interactive seeded sessions Omarchy needs." >&2
+    exit 1
+  fi
 fi
diff --git a/test/shell.d/default-agent-test.sh b/test/shell.d/default-agent-test.sh
index 5b4512f1..fbd60f31 100644
--- a/test/shell.d/default-agent-test.sh
+++ b/test/shell.d/default-agent-test.sh
@@ -431,8 +431,10 @@ assert_launched() {
     fail "$agent launch $description" "expected: ${expected[*]}\nactual: ${actual[*]}"
 
   for ((index = 0; index < ${#expected[@]}; index++)); do
-    [[ ${actual[$index]} == ${expected[$index]} ]] ||
-      fail "$agent launch $description" "expected: ${expected[*]}\nactual: ${actual[*]}"
+    case ${actual[$index]} in
+    "${expected[$index]}") ;;
+    *) fail "$agent launch $description" "expected: ${expected[*]}\nactual: ${actual[*]}" ;;
+    esac
   done
 }
 
@@ -462,10 +464,18 @@ assert_launch claude claude --permission-mode auto -- "Review this project"
 assert_launch codex codex --approve-for-me -- "Review this project"
 assert_launch crush crush run "Review this project"
 assert_launch grok grok --permission-mode bypassPermissions -- "Review this project"
+assert_launch hermes env -u HERMES_SESSION_SOURCE hermes chat --yolo --tui "--query=Review this project"
 assert_launch agy agy --dangerously-skip-permissions --prompt-interactive "Review this project"
 assert_launch copilot copilot --allow-all --interactive "Review this project"
 pass "agent launcher adapts initial prompts for every supported agent"
 
+literal_hermes_prompt=$' --help !Crash /quit {$(touch must-not-run)}\ntrailing\\ '
+printf '%s\n' "hermes" >"$agent_file"
+omarchy-agent-prompt "$literal_hermes_prompt"
+assert_launched hermes "binds its literal initial prompt" env -u HERMES_SESSION_SOURCE \
+  hermes chat --yolo --tui "--query=$literal_hermes_prompt"
+pass "Hermes receives prompted launches as one literal query argument"
+
 assert_bypass pi pi
 assert_bypass omp omp --auto-approve
 assert_bypass opencode opencode --auto
@@ -474,6 +484,7 @@ assert_bypass claude claude --permission-mode auto
 assert_bypass codex codex --approve-for-me
 assert_bypass crush crush --yolo
 assert_bypass grok grok --permission-mode bypassPermissions
+assert_bypass hermes hermes --yolo
 assert_bypass agy agy --dangerously-skip-permissions
 assert_bypass copilot copilot --allow-all
 pass "agent launcher skips permission prompts for every supported agent"
diff --git a/test/shell.d/hermes-cli-test.sh b/test/shell.d/hermes-cli-test.sh
index 88319dc9..83b516e9 100755
--- a/test/shell.d/hermes-cli-test.sh
+++ b/test/shell.d/hermes-cli-test.sh
@@ -26,7 +26,10 @@ SH
 cat >"$mock_bin/mise" <<'SH'
 #!/bin/bash
 printf '%s\0' "$@" >>"$OMARCHY_TEST_MISE_LOG"
-[[ $1 == "where" && ${OMARCHY_TEST_MISE_WHERE_OK:-0} == 1 ]] && exit 0
+if [[ $1 == "where" && ${OMARCHY_TEST_MISE_WHERE_OK:-0} == 1 ]]; then
+  printf '%s\n' "$OMARCHY_TEST_MISE_ROOT"
+  exit 0
+fi
 [[ $1 != "where" ]]
 SH
 
@@ -35,6 +38,7 @@ chmod +x "$mock_bin"/*
 run_installer() {
   OMARCHY_TEST_DESKTOP_INSTALLED="$1" \
     OMARCHY_TEST_MISE_WHERE_OK="${OMARCHY_TEST_MISE_WHERE_OK:-0}" \
+    OMARCHY_TEST_MISE_ROOT="$test_tmp/mise" \
     OMARCHY_TEST_MISE_LOG="$mise_log" \
     HOME="$test_home" \
     PATH="$mock_bin:$PATH" \
@@ -88,10 +92,17 @@ pass "takeover removes an unhealthy mise copy"
 rm -rf "$test_home/.hermes"
 rm -f "$test_home/.local/bin/hermes"
 run_installer 1 --check && fail "--check reports Hermes missing before the app installs it"
-# The venv command answers --version, as the real one does: foreign wrappers
-# below exec it, and the installer probes them by running exactly that.
+# The venv command answers the readiness probes, as the real one does: foreign
+# wrappers below exec it, and the installer runs both before trusting them.
 mkdir -p "$test_home/.hermes/hermes-agent/venv/bin"
-printf '%s\n' "#!/bin/bash" 'echo "hermes-agent 0.0.0-test"' >"$test_home/.hermes/hermes-agent/venv/bin/hermes"
+cat >"$test_home/.hermes/hermes-agent/venv/bin/hermes" <<'SH'
+#!/bin/bash
+if [[ ${1:-} == "chat" && ${2:-} == "--help" ]]; then
+  [[ ${OMARCHY_TEST_HERMES_CAPABLE:-1} == 1 ]] && echo "--oneshot"
+else
+  echo "hermes-agent 0.0.0-test"
+fi
+SH
 chmod +x "$test_home/.hermes/hermes-agent/venv/bin/hermes"
 run_installer 1 --check && fail "--check waits for the install to finish, not just the venv"
 touch "$test_home/.hermes/hermes-agent/.hermes-bootstrap-complete"
@@ -123,6 +134,14 @@ run_installer 0 --now || fail "--now over a foreign hermes command returns succe
   fail "a foreign hermes command is left untouched"
 pass "a foreign hermes command is preserved and satisfies --check"
 
+OMARCHY_TEST_HERMES_CAPABLE=0 run_installer 0 --check &&
+  fail "--check rejects a foreign Hermes without native prompted sessions"
+OMARCHY_TEST_HERMES_CAPABLE=0 run_installer 0 &&
+  fail "installing refuses a foreign Hermes without native prompted sessions"
+[[ $(cat "$test_home/.local/bin/hermes") == "$official_body" ]] ||
+  fail "an older foreign Hermes command is left untouched"
+pass "a foreign Hermes must support native prompted sessions"
+
 # Broken foreign paths are still foreign. They cannot be used, so --check says
 # so and the installer refuses rather than replacing them.
 printf '%s\n' "$official_body" >"$test_home/.local/bin/hermes"
@@ -211,6 +230,23 @@ grep -q "stale template" "$test_home/.local/bin/hermes" && fail "reinstalling re
 grep -q "exec env -u UV_PYTHON mise x" "$test_home/.local/bin/hermes" || fail "the refreshed stub is the current template"
 pass "reinstalling refreshes the Omarchy stub"
 
+mkdir -p "$test_tmp/mise/hermes-agent/lib/python$python_pin"
+: >"$mise_log"
+OMARCHY_TEST_MISE_WHERE_OK=1 run_installer 0 || fail "reinstalling replaces an older owned Hermes environment"
+tr '\0' '\n' <"$mise_log" | grep -q '^rm$' || fail "an older owned Hermes environment is removed from mise config"
+tr '\0' '\n' <"$mise_log" | grep -q '^uninstall$' || fail "an older owned Hermes environment is uninstalled"
+pass "reinstalling replaces an older owned Hermes environment"
+
+rm -f "$test_home/.local/bin/hermes"
+: >"$mise_log"
+OMARCHY_TEST_MISE_WHERE_OK=1 run_installer 0 &&
+  fail "installing refuses to claim an unmarked Hermes mise environment"
+tr '\0' '\n' <"$mise_log" | grep -Eq '^(rm|uninstall)$' &&
+  fail "an unmarked Hermes mise environment is never removed"
+[[ ! -e $test_home/.local/bin/hermes ]] ||
+  fail "an unmarked Hermes mise environment is not given an Omarchy wrapper"
+pass "a Hermes mise environment needs wrapper ownership before replacement"
+
 # install/user/mise.sh is sourced by install/user/all.sh through run_logged,
 # which runs it under `bash -eE` and hands its exit code back to
 # omarchy-provision-user's `set -euo pipefail`. Everything that finalizes a user
@@ -349,8 +385,14 @@ run_ready_check() {
 
 run_ready_check && fail "--check rejects the app's wrapper when its runtime is gone"
 
-printf '%s\n' "#!/bin/bash" 'echo "hermes-agent 0.0.0-test"' \
-  >"$ready_home/.hermes/hermes-agent/venv/bin/hermes"
+cat >"$ready_home/.hermes/hermes-agent/venv/bin/hermes" <<'SH'
+#!/bin/bash
+if [[ ${1:-} == "chat" && ${2:-} == "--help" ]]; then
+  echo "--oneshot"
+else
+  echo "hermes-agent 0.0.0-test"
+fi
+SH
 chmod +x "$ready_home/.hermes/hermes-agent/venv/bin/hermes"
 run_ready_check || fail "--check accepts the app's wrapper once it runs"
 pass "readiness runs the app's command rather than trusting its marker"