feat(neomutt): add keybindings, sidebar colors, mailcap, and urlscan integration

- Remap sidebar-open from Ctrl+O to 'o' for single-key access
- Add Enter/l/h/0/$ keybindings across index, pager, and browser modes
- Add macros: O (mbsync sync), gx (urlscan link extraction), gl (flag legend)
- Add extraConfig with abort_key, mailcap_path, and auto_view for attachments
- Add mailcap for w3m/html, image/pdf/video/audio openers via xdg-open
- Add flag_legend.txt help file accessible via 'gl'
- Add home.packages for urlscan and w3m
- Add checkStatsInterval = 20

- Add sidebar colors (background, divider, ordinary, new, flagged, spool_file, highlight, indicator)
- Add prompt, progress, stripe_odd/stripe_even, and attach_headers colors
- Add index_collapsed, index_label, index_tag, and index_tags color targets
- Fix indicator to use brightblack background instead of blue for better contrast
- Extend quoted colors from 4 to 9 levels for deeply nested replies
- Change Date header color to green
- Update index_format with padding for cleaner alignment

- Add mailboxes, Expunge = Both, and notmuch virtual mailboxes to email example

3 files changed, 193 insertions, 16 deletions

diff --git a/modules/private/email.example.nix b/modules/private/email.example.nix
index 2f48b90..9fc9ee2 100644
--- a/modules/private/email.example.nix
+++ b/modules/private/email.example.nix
@@ -12,6 +12,9 @@
       neomutt = {
         enable = true;
         mailboxType = "maildir";
+        extraConfig = ''
+          mailboxes =Inbox ="[Gmail]/Drafts" ="[Gmail]/Sent Mail" ="[Gmail]/Trash"
+        '';
       };
 
       folders = {
@@ -34,10 +37,19 @@
           SyncState = "*";
           Sync = "All";
           CopyArrivalDate = "yes";
+          Expunge = "Both";
         };
       };
 
-      notmuch.enable = true;
+      notmuch = {
+        enable = true;
+        neomutt.virtualMailboxes = [
+          {
+            name = "All Mail";
+            query = "folder:example/Inbox or folder:\"example/[Gmail]/Sent Mail\"";
+          }
+        ];
+      };
     };
   };
 }
diff --git a/modules/programs/neomutt/default.nix b/modules/programs/neomutt/default.nix
index 940ce9a..e489328 100644
--- a/modules/programs/neomutt/default.nix
+++ b/modules/programs/neomutt/default.nix
@@ -2,21 +2,76 @@
 {
   config,
   lib,
+  pkgs,
   ...
 }:
-
 {
   imports = [
     ./assertions.nix
     ./theme.nix
   ];
-
   config = lib.mkIf config.programs.neomutt.enable {
+    home.packages = [
+      pkgs.urlscan
+      pkgs.w3m
+    ];
+
+    xdg.configFile."neomutt/mailcap".text = ''
+      text/html; w3m -dump -T text/html '%s'; copiousoutput; nametemplate=%s.html
+      text/html; $BROWSER '%s'; nametemplate=%s.html
+      image/*; xdg-open '%s' &
+      application/pdf; xdg-open '%s'; nametemplate=%s.pdf
+      video/*; xdg-open '%s' &
+      audio/*; xdg-open '%s' &
+      application/*; xdg-open '%s' &
+    '';
+
+    xdg.configFile."neomutt/flag_legend.txt".text = ''
+      NeoMutt Index Flags
+      ===================
+
+      Message state ($flag_chars)
+        N   New       - unread, arrived since you last checked
+        O   Old       - unread, but seen in a previous session
+        D   Deleted   - marked for deletion (pending expunge)
+        d   Att-del   - has attachments marked for deletion
+        !   Flagged   - important (toggle with F)
+        *   Tagged    - selected for a bulk operation (toggle with t)
+        r   Replied   - you've replied to this message
+        S   Signed    - PGP/SMIME signed
+        P   Encrypted - PGP/SMIME encrypted
+        s   Cert      - contains a S/MIME certificate/key
+        K   PGP key   - contains a PGP public key
+        (blank)       - read, nothing else notable
+
+      Addressing ($to_chars)
+        +   To you only     - sent to you and only you
+        T   To (with others) - you're in the To: list, among others
+        C   Cc only          - you're only in the Cc: list
+        F   From you         - sent by you
+        L   Mailing list     - sent to a list you're subscribed to
+        (blank)              - not in To/Cc (e.g. Bcc, unlisted)
+
+      Press q to close.
+    '';
+
     programs.neomutt = {
       sidebar.enable = true;
       sort = "reverse-threads";
       vimKeys = true;
       unmailboxes = true;
+      checkStatsInterval = 20;
+
+      extraConfig = ''
+        # cancel any prompt/command-line entry with Esc, vim-style
+        set abort_key = "<Esc>"
+
+        # attachments: use our mailcap for dedicated openers,
+        # and auto-render html/images inline where sensible
+        set mailcap_path = "~/.config/neomutt/mailcap"
+        auto_view text/html image/png image/jpeg image/gif application/pdf
+      '';
+
       binds = [
         {
           map = [
@@ -35,13 +90,75 @@
           action = "sidebar-next";
         }
         {
+          # select the highlighted mailbox directly, no Ctrl+O needed
           map = [
             "index"
             "pager"
           ];
-          key = "\\CO";
+          key = "o";
           action = "sidebar-open";
         }
+
+        {
+          map = [ "index" ];
+          key = "<Return>";
+          action = "display-message";
+        }
+        {
+          map = [ "browser" ];
+          key = "<Return>";
+          action = "select-entry";
+        }
+        {
+          map = [ "attach" ];
+          key = "<Return>";
+          action = "view-attach";
+        }
+        {
+          map = [
+            "alias"
+            "query"
+          ];
+          key = "<Return>";
+          action = "select-entry";
+        }
+        {
+          map = [ "pager" ];
+          key = "<Return>";
+          action = "next-page";
+        }
+
+        {
+          map = [ "index" ];
+          key = "l";
+          action = "display-message";
+        }
+        {
+          map = [ "pager" ];
+          key = "h";
+          action = "exit";
+        }
+        {
+          map = [ "pager" ];
+          key = "l";
+          action = "next-unread";
+        }
+        {
+          map = [ "index" ];
+          key = "h";
+          action = "collapse-thread";
+        }
+
+        {
+          map = [ "pager" ];
+          key = "0";
+          action = "top";
+        }
+        {
+          map = [ "pager" ];
+          key = "$";
+          action = "bottom";
+        }
       ];
 
       macros = [
@@ -53,6 +170,23 @@
           key = "O";
           action = "<sync-mailbox><shell-escape>mbsync -a<enter><sync-mailbox>";
         }
+        {
+          # gx: extract links from the current message and open one, vim-netrw style
+          map = [
+            "index"
+            "pager"
+          ];
+          key = "gx";
+          action = "<pipe-message>urlscan<Enter>";
+        }
+        {
+          map = [
+            "index"
+            "pager"
+          ];
+          key = "gl";
+          action = "<shell-escape>less ~/.config/neomutt/flag_legend.txt<enter>";
+        }
       ];
     };
   };
diff --git a/modules/programs/neomutt/theme.nix b/modules/programs/neomutt/theme.nix
index 8e57645..60427fc 100644
--- a/modules/programs/neomutt/theme.nix
+++ b/modules/programs/neomutt/theme.nix
@@ -9,10 +9,10 @@
     # Base16 OneDark Dark terminal colors for neomutt
     # Each column in the index receives a distinct color to keep the UI organized.
 
-    set index_format = "%4C│ %Z │ %{%d/%m %H:%M} │ %-25.25a │ %s"
+    set index_format = " %4C │ %Z │ %{%d/%m %H:%M} │ %-25.25a │ %s%* "
 
     # --- Basic UI Colors --------------------------------------------------
-    # fg              bg
+    #     target      foreground    background
     color normal      white         default     # base05 (Standard text)
     color error       red           default     # base08 (Red)
     color tilde       brightblack   default     # base03 (Dark Grey)
@@ -20,20 +20,29 @@
     color markers     red           default     # base08 (Red)
     color attachment  magenta       default     # base0E (Magenta)
     color search      magenta       default     # base0E (Magenta)
+    color prompt      cyan          default     # base0C (Questions/prompts)
+    color progress    black         yellow      # base0A bg (Progress bar)
 
     # Selected row and status bar
-    color status      white         brightblack # base05 on base03
-    color indicator   black         blue        # base00 on base0D (Selected email)
-    color tree        brightblack   default     # base03 (Thread arrows)
+    color status      white         brightblack # base05  on base03
+    color indicator   default       brightblack # default on base03 (Selected email)
+    color tree        magenta       default     # base03  (Thread arrows)
+
+    # Whole-line fallback for the index (base for anything not caught below)
+    color index       white         default     # base05
 
     # --- Index Columns (The Multi-Color Table) ----------------------------
     # Applies distinct colors to specific columns for ALL messages (~A)
-    color index_number  white       default "~A"  # base05 (Fixed: was brightblack)
-    color index_date    green       default "~A"  # base0B (Green)
-    color index_flags   red         default "~A"  # base08 (Red)
-    color index_size    cyan        default "~A"  # base0C (Cyan)
-    color index_author  yellow      default "~A"  # base0A (Yellow)
-    color index_subject white       default "~A"  # base05 (Standard text for Read messages)
+    color index_number    cyan        default "~A"  # base05 (Fixed: was brightblack)
+    color index_date      green       default "~A"  # base0B (Green)
+    color index_flags     red         default "~A"  # base08 (Red)
+    color index_size      cyan        default "~A"  # base0C (Cyan)
+    color index_author    yellow      default "~A"  # base0A (Yellow)
+    color index_subject   white       default "~A"  # base05 (Standard text for Read messages)
+    color index_collapsed yellow      default        # base0A (Collapsed thread count, %M)
+    color index_label     magenta     default        # base0E (Message label, %y %Y)
+    color index_tag       cyan        default        # base0C (Message tags, %G)
+    color index_tags      cyan        default        # base0C (Transformed tags, %g %J)
 
     # --- Index Message States ---------------------------------------------
     # By targeting *only* `index_subject`, we preserve your multi-color 
@@ -57,11 +66,18 @@
     color index_subject blue        default "~v~(~N)"   # Collapsed with unread inside
     color index_subject red         default "~v~(~F)"   # Collapsed with flagged inside
 
+    # Subtle zebra striping between adjacent index rows (barely-there contrast)
+    color stripe_odd  default default
+    color stripe_even default default
+
     # --- Message Headers --------------------------------------------------
     color hdrdefault  cyan          default     # base0C
     color header      yellow        default "^(From|To|Cc|Bcc)" # base0A
     color header      blue          default "^(Subject)"        # base0D
-    color header      brightblack   default "^(Date)"           # base03
+    color header      green         default "^(Date)"           # base03
+
+    # Attachment header lines (shown above each MIME part in the pager)
+    color attach_headers cyan       default
 
     # --- Message Body -----------------------------------------------------
     color quoted      blue          default     # base0D
@@ -69,6 +85,11 @@
     color quoted2     yellow        default     # base0A
     color quoted3     red           default     # base08
     color quoted4     magenta       default     # base0E
+    color quoted5     blue          default     # base0D (cycle repeats)
+    color quoted6     cyan          default     # base0C
+    color quoted7     yellow        default     # base0A
+    color quoted8     red           default     # base08
+    color quoted9     magenta       default     # base0E
 
     color signature   green         default     # base0B
     color bold        white         default     # base05
@@ -81,5 +102,15 @@
     color body        green         default "(Good signature)"
     color body        red           default "(BAD signature)"
     color body        brightblack   default "^gpg: "
+
+    # --- Sidebar (was completely unset despite sidebar.enable = true) -----
+    color sidebar_background default     default     # transparent, blends with terminal bg
+    color sidebar_divider    white       default    # base03 (matches old tree color)
+    color sidebar_ordinary   white       default    # base05 (normal mailbox entries)
+    color sidebar_new        green       default    # base0B (mailboxes with new mail)
+    color sidebar_flagged    red         default    # base08 (mailboxes with flagged mail)
+    color sidebar_spool_file yellow      default    # base0A (your inbox/spool)
+    color sidebar_highlight  white       brightblack # base05 on base03 (cursor position)
+    color sidebar_indicator  default     brightblack # default on base03 (currently open mailbox)
   '';
 }