diff --git a/functions/__config_settings_subcats.fish b/functions/__config_settings_subcats.fish
new file mode 100644
index 0000000..52a2ad8
--- /dev/null
+++ b/functions/__config_settings_subcats.fish
@@ -0,0 +1,65 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# SYNOPSIS
+#   __config_settings_subcats <category_variable>
+#
+# DESCRIPTION
+#   Prints the sub-category rows for one C1-C6 category, one per line as
+#   "<slug>\t<label>\t<description>". This is a fish-native copy of the
+#   taxonomy authored in docs/manual/08-components-reference/*.md (Task 9)
+#   -- kept here as a static table rather than parsed from markdown at
+#   draw time, since config-settings redraws on every keypress and every
+#   terminal resize.
+#
+# ARGUMENTS
+#   category_variable  One of the six __fish_config_op_<category> names
+#
+# EXIT STATUS
+#   0  Always
+#
+# RETURNS
+#   Tab-separated "<slug>\t<label>\t<description>" rows, one per line
+#
+# EXAMPLE
+#   __config_settings_subcats __fish_config_op_aliases
+function __config_settings_subcats --description 'List the sub-categories for one opinionated-component category'
+    switch $argv[1]
+        case __fish_config_op_aliases
+            printf '%s\t%s\t%s\n' \
+                filesystem Filesystem "ls, cat, cd, du, mkdir, rm, mv, zoxide" \
+                search Search "rg" \
+                network Network "ping, ssh, yt-dlp" \
+                monitor Monitor "top" \
+                shell-tools Shell-tools "bash, less, help" \
+                dev-tools Dev-tools "claude, edit, agy"
+        case __fish_config_op_autoexec
+            printf '%s\t%s\t%s\n' \
+                plugin-management Plugins "Fisher bootstrap" \
+                pkg-wrappers Pkg-wrappers "paru/yay wrapper generation" \
+                venv Venv "Python auto-activation" \
+                telemetry Telemetry "WakaTime hook bootstrap" \
+                sync Sync "auto-pull, user-dots symlink"
+        case __fish_config_op_overrides
+            printf '%s\t%s\t%s\n' \
+                key-bindings Key-bindings "vi-mode, autopair, puffer, bang-bang" \
+                environment Environment "PATH, PAGER, EDITOR, CDPATH" \
+                prompt Prompt "Starship, right prompt, theme + FZF colors"
+        case __fish_config_op_integrations
+            printf '%s\t%s\t%s\n' \
+                terminal-abbrs Term-abbrs "Kitty/WezTerm abbreviations" \
+                window-mgmt Window-mgmt "spwin, tab, split" \
+                notifications Notifications "done, WakaTime hook" \
+                history-logs History-logs "hist, logs" \
+                pkg-upgrade Pkg-upgrade "upgrade"
+        case __fish_config_op_logging
+            printf '%s\t%s\t%s\n' \
+                terminal-capture Term-capture "Kitty watcher, smart_exit scrollback" \
+                multiplexer-capture Multiplexer "tmux, zellij" \
+                pkg-logs Pkg-logs "paru/yay AUR log wrappers"
+        case __fish_config_op_greeting
+            printf '%s\t%s\t%s\n' \
+                first-run First-run "welcome banner" \
+                greeting-message Greeting "fish_greeting override"
+    end
+end
diff --git a/functions/config-settings.fish b/functions/config-settings.fish
index 5730306..452f696 100644
--- a/functions/config-settings.fish
+++ b/functions/config-settings.fish
@@ -110,6 +110,12 @@ function config-settings --description 'Interactive TUI for managing fish config
         __fish_config_op_greeting \
         __fish_config_opinionated
 
+    # ── Drill-down navigation state (Universal/Session pages only) ────────
+    # in_subcat: 1 while viewing a category's sub-category page (Enter to
+    # open, Escape to back out). subcat_row: cursor row within that page.
+    set -l in_subcat 0
+    set -l subcat_row 0
+
     # ── Value-page row metadata (parallel: var / type) ────────────────────
     set -l sponge_vars sponge_delay sponge_purge_only_on_exit sponge_allow_previously_successful sponge_successful_exit_codes __fish_sponge_extra_sensitive
     set -l sponge_types int bool bool list list
@@ -143,9 +149,17 @@ function config-settings --description 'Interactive TUI for managing fish config
     function __cs_dispatch_draw --no-scope-shadowing
         switch $cur_page
             case 0
-                __config_settings_draw $cur_row universal $toggle_vars
+                if test $in_subcat -eq 1
+                    __config_settings_draw_subcat $subcat_row universal $toggle_vars[(math $cur_row + 1)]
+                else
+                    __config_settings_draw $cur_row universal $toggle_vars
+                end
             case 1
-                __config_settings_draw $cur_row session $toggle_vars
+                if test $in_subcat -eq 1
+                    __config_settings_draw_subcat $subcat_row session $toggle_vars[(math $cur_row + 1)]
+                else
+                    __config_settings_draw $cur_row session $toggle_vars
+                end
             case 2
                 __config_settings_draw_value $cur_row sponge
             case 3
@@ -174,12 +188,22 @@ function config-settings --description 'Interactive TUI for managing fish config
 
         switch $key
             case up k
-                set cur_row (math "max(0, $cur_row - 1)")
+                if test $in_subcat -eq 1
+                    set subcat_row (math "max(0, $subcat_row - 1)")
+                else
+                    set cur_row (math "max(0, $cur_row - 1)")
+                end
             case down j
-                # Hoist the page index: fish cannot expand a command-substitution
-                # index inside a quoted math string.
-                set -l pidx (math $cur_page + 1)
-                set cur_row (math "min($page_rows[$pidx] - 1, $cur_row + 1)")
+                if test $in_subcat -eq 1
+                    # TODO(Task 18): replace the stubbed 4-row max with the real
+                    # per-category count from __config_settings_subcats.
+                    set subcat_row (math "min(3, $subcat_row + 1)")
+                else
+                    # Hoist the page index: fish cannot expand a command-substitution
+                    # index inside a quoted math string.
+                    set -l pidx (math $cur_page + 1)
+                    set cur_row (math "min($page_rows[$pidx] - 1, $cur_row + 1)")
+                end
             case tab
                 set cur_page (math "($cur_page + 1) % 4")
                 set cur_row 0
@@ -246,7 +270,12 @@ function config-settings --description 'Interactive TUI for managing fish config
                     end
                 end
             case enter
-                if test $cur_page -ge 2
+                if test $cur_page -le 1
+                    if test $in_subcat -eq 0 -a $cur_row -le 5
+                        set in_subcat 1
+                        set subcat_row 0
+                    end
+                else if test $cur_page -ge 2
                     set -l v_vars $sponge_vars
                     set -l v_types $sponge_types
                     set -l v_defaults $sponge_defaults
@@ -313,8 +342,14 @@ function config-settings --description 'Interactive TUI for managing fish config
                         set did_redraw 1
                     end
                 end
-            case q Q quit escape
+            case q Q quit
                 break
+            case escape
+                if test $in_subcat -eq 1
+                    set in_subcat 0
+                else
+                    break
+                end
         end
 
         # Skip redraw entirely when the key reader timed out with no resize