refactor(thunderbird): trim user.js to curated high-signal prefs

Drop the hand-rolled kitchen-sink config in favour of a smaller set
inspired by HorlogeSkynet/thunderbird-user.js. Removes prefs that were
either restating Mozilla/Arch defaults (telemetry, app.update),
Firefox-only (extensions.screenshots), or guessed/stale
(mail.folder_widget.view_flags).

Keeps: remote-image block, no read receipts, plain-text compose with
format=flowed, no UA header leak, no Referer/prefetch, safe-browsing
off, DNT on, system gpg-agent for OpenPGP, vertical pane, Monday
calendar start.

1 files changed, 40 insertions, 65 deletions

diff --git a/thunderbird/user.js b/thunderbird/user.js
index c7da235..29b0dc1 100644
--- a/thunderbird/user.js
+++ b/thunderbird/user.js
@@ -1,81 +1,56 @@
 /*
  * Thunderbird user.js — non-private configuration tracked in dotfiles.
- * Accounts, passwords, mailboxes, calendar/contact data, and per-machine
- * state stay local (prefs.js, logins.json, key4.db, ImapMail/, etc.).
+ *
+ * Tight, curated set. Each pref changes a behaviour I actually want;
+ * defaults already-shipped by Mozilla/Arch are NOT restated.
+ *
+ * Inspired by (not copied from) HorlogeSkynet/thunderbird-user.js.
  * Deployed by run_onchange_after_deploy-thunderbird.sh.tmpl.
+ * Accounts, passwords, mailboxes, calendar/contact data stay local.
  */
 
-/** Startup & updates **/
-user_pref("app.update.auto", false);                              // Arch handles updates
-user_pref("app.update.enabled", false);
-user_pref("mail.shell.checkDefaultClient", false);
-user_pref("mailnews.start_page.enabled", false);                  // no "what's new" tab
-user_pref("browser.rights.3.shown", true);
-user_pref("mail.spotlight.firstRunDone", true);
-user_pref("mail.winsearch.firstRunDone", true);
-
-/** Telemetry & data reporting — off **/
-user_pref("toolkit.telemetry.enabled", false);
-user_pref("toolkit.telemetry.unified", false);
-user_pref("toolkit.telemetry.archive.enabled", false);
-user_pref("toolkit.telemetry.newProfilePing.enabled", false);
-user_pref("toolkit.telemetry.shutdownPingSender.enabled", false);
-user_pref("toolkit.telemetry.updatePing.enabled", false);
-user_pref("toolkit.telemetry.bhrPing.enabled", false);
-user_pref("toolkit.telemetry.firstShutdownPing.enabled", false);
-user_pref("datareporting.healthreport.uploadEnabled", false);
-user_pref("datareporting.policy.dataSubmissionEnabled", false);
-user_pref("browser.ping-centre.telemetry", false);
-user_pref("toolkit.coverage.opt-out", true);
-user_pref("toolkit.coverage.endpoint.base", "");
-
-/** Safe browsing & connectivity probes — off (we trust our mail sources) **/
-user_pref("browser.safebrowsing.downloads.enabled", false);
-user_pref("browser.safebrowsing.malware.enabled", false);
-user_pref("browser.safebrowsing.phishing.enabled", false);
-user_pref("network.captive-portal-service.enabled", false);
-user_pref("network.connectivity-service.enabled", false);
-user_pref("network.prefetch-next", false);
-user_pref("network.dns.disablePrefetch", true);
-
 /** Reading — no remote content, no read receipts **/
-user_pref("mailnews.message_display.disable_remote_image", true); // block tracking pixels
-user_pref("mail.phishing.detection.enabled", true);
-user_pref("mail.mdn.report.enabled", false);                      // never send read receipts
-user_pref("mail.incorporate.return_receipt", 0);                  // never request
-user_pref("mail.server.default.mark_old_as_read", false);
-user_pref("mailnews.mark_message_read.auto", true);
-user_pref("mailnews.mark_message_read.delay", true);
-user_pref("mailnews.mark_message_read.delay.interval", 2);
+user_pref("mailnews.message_display.disable_remote_image", true);
+user_pref("mail.inline_attachments", false);
+user_pref("mail.mdn.report.enabled", false);
+user_pref("mail.incorporate.return_receipt", 0);
 
-/** Compose — plain text first, flowed wrap at 72 **/
+/** Compose — plain text, format=flowed wrap at 72 **/
 user_pref("mail.identity.default.compose_html", false);
+user_pref("mail.default_html_action", 2);
 user_pref("mailnews.send_plaintext_flowed", true);
+user_pref("mail.compose.default_to_paragraph", false);
 user_pref("mailnews.wraplength", 72);
-user_pref("mail.strictly_mime", false);
-user_pref("mail.SpellCheckBeforeSend", true);
-user_pref("mail.spellcheck.inline", true);
 
-/** UI **/
-user_pref("mail.pane_config.dynamic", 2);                          // vertical: message pane on the right
-user_pref("mail.threadpane.table.horizontal_scroll", true);
-user_pref("mailnews.default_sort_order", 2);                       // descending
-user_pref("mailnews.default_sort_type", 18);                       // by date
-user_pref("mail.folder_widget.view_flags", 1);                     // unified folders mode
-user_pref("mail.biff.play_sound", false);                          // use mako notifications only
-user_pref("mail.biff.show_alert", true);
-user_pref("mail.biff.alert.show_preview", false);                  // don't leak body to notification
-user_pref("mail.biff.alert.show_sender", true);
-user_pref("mail.biff.alert.show_subject", true);
+/** Outgoing headers — don't leak TB version **/
+user_pref("mailnews.headers.showUserAgent", false);
+user_pref("general.useragent.override", "");
 
-/** Calendar **/
-user_pref("calendar.week.start", 1);                               // Monday
-user_pref("calendar.view.timeIndicator.interval", 1);
-user_pref("calendar.alarms.playsound", false);
-user_pref("calendar.alarms.show", true);
-user_pref("calendar.timezone.useSystemTimezone", true);
+/** Network — no Referer, no prefetch **/
+user_pref("network.http.sendRefererHeader", 0);
+user_pref("network.prefetch-next", false);
+user_pref("network.dns.disablePrefetch", true);
+user_pref("network.captive-portal-service.enabled", false);
+
+/** Safe-browsing — off. TB rarely opens arbitrary URLs; avoids Google contact. **/
+user_pref("browser.safebrowsing.malware.enabled", false);
+user_pref("browser.safebrowsing.phishing.enabled", false);
+user_pref("browser.safebrowsing.downloads.enabled", false);
 
-/** Privacy **/
+/** Privacy signal + local history off **/
 user_pref("privacy.donottrackheader.enabled", true);
 user_pref("places.history.enabled", false);
 user_pref("browser.formfill.enable", false);
+
+/** OpenPGP — use system gpg-agent/keys instead of TB's internal store **/
+user_pref("mail.openpgp.allow_external_gnupg", true);
+
+/** UI / notifications — mako handles the rest **/
+user_pref("mail.shell.checkDefaultClient", false);
+user_pref("mail.biff.play_sound", false);
+user_pref("mail.biff.show_alert", false);
+user_pref("mail.pane_config.dynamic", 2);
+
+/** Calendar **/
+user_pref("calendar.week.start", 1);
+user_pref("calendar.timezone.useSystemTimezone", true);