fix(mime): text/plain falls through to Text Editor on live (#119)

A singleton default naming code.desktop left the live ISO with no text
handler — GIO skips missing .desktop files and offers nothing. Prefer
vscode when present, then org.gnome.TextEditor.desktop. Live also gains
mpv (video defaults had the same hole; free via the template pin).

checks.live-baseline-apps now requires every Default Applications key
to resolve to a present .desktop on live (HM + system path) and on the
default template install. Proved to fail on a vscode-only text/plain.

Verified: V2 (live-baseline-apps green + prove-to-fail); V0 flake check.

agent/BACKLOG.md

@@ -55,31 +55,6 @@ template source. Pass = Chromium launches after installation and HTTP/HTTPS
 mime defaults resolve to `chromium-browser.desktop` (and the intended live-ISO
 browser posture is explicit).
 
-### 119. `text/plain` names vscode, which the live ISO does not ship
-
-Found while shipping #103 (2026-07-14), deliberately not fixed there — same
-bug class as #94, one mime key over. `modules/home/mime.nix:48` assigns
-`text/plain = code.desktop`, and vscode ships only in the **template**, never
-on the live ISO. GIO silently skips an entry whose desktop file is absent, so
-opening a text file in the live session finds no handler at all — the exact
-shape of the no-default-browser bug, and now the only one left of its kind
-since #103 put chromium on the live medium.
-
-Two ways it bites, and a fix should settle both: (1) the live session, which
-now ships `gnome-text-editor` (`org.gnome.TextEditor.desktop`) — the obvious
-live handler; (2) any installed machine where the user takes the template at
-its word and deletes the `vscode` line (opt-out = delete the line, per the
-option-surface convention), which silently breaks `text/plain` with no warning.
-
-The general trap is worth fixing once rather than per-key: a mime default
-naming a package the profile does not carry is invisible until a user
-double-clicks a file. `checks.live-baseline-apps` now guards exactly this for
-HTTPS (asserts the named .desktop is present, not merely named) — the cheap
-version of this item is extending that assertion to every key in
-`defaultApplications`, which would have caught both #94 and this. Pass = no
-mime default names a desktop entry the profile lacks, on the live ISO and on
-a template install, and a guard fails on a regression.
-
 ### 95. Live ISO/install: Ghostty does not open
 
 Reproduce from the launcher and a terminal, capture its stderr/journal, and

agent/HARDWARE-QUEUE.md

@@ -421,12 +421,11 @@ the **T14s** (webcam case).
       **LibreOffice** (Writer), **Text Editor**, **Amberol**, **Snapshot**.
       **Pass** = all five are *listed in the launcher* and each opens a window.
       Also: a `.html` file opens in Chromium (the HTTPS mime default now names
-      a browser that is present — #94's exact bug). Firefox is deliberately
+      a browser that is present — #94's exact bug), and a `.txt` file opens in
-      absent; its absence is correct, not a miss.
+      **Text Editor** (`text/plain` falls through to
-      **Known-not-covered:** a `.txt` file has no handler on the live ISO —
+      `org.gnome.TextEditor.desktop` after #119; vscode remains preferred on
-      `text/plain` still names vscode, which the live medium never ships
+      template installs). Firefox is deliberately absent; its absence is
-      (BACKLOG #119). Text Editor opening from the launcher is the pass here;
+      correct, not a miss.
-      double-clicking a text file is #119's problem, so don't file it twice.
 
 ## AMD dev box only
 - [ ] **#118 smartd still runs where drives DO have SMART** (this commit) — the

agent/JOURNAL.md

@@ -19,6 +19,26 @@ Template:
 
 ---
 
+## 2026-07-15 — #119: mime defaults must name a present .desktop (this commit)
+- **Task:** BACKLOG #119 — `text/plain` named vscode, which the live ISO never
+  ships (same GIO-skip trap as #94, one key over).
+- **Did:** `text/plain` is now an ordered fallback
+  `code.desktop` → `org.gnome.TextEditor.desktop` (HM tries the next when the
+  preferred is missing). Live profile gains `mpv` too — video mime defaults
+  had the same hole and the package is free via the template pin. Extended
+  `checks.live-baseline-apps` so every `[Default Applications]` key has at
+  least one listed `.desktop` on **live** (HM path + system path for thunar)
+  and on the **default template install**.
+- **Verified:** **V2** — check green; mimeapps.list renders
+  `text/plain=code.desktop;org.gnome.TextEditor.desktop`; **proved to fail**
+  when `text/plain` is a vscode-only singleton. V0 flake check green.
+- **Pending:** V3 launch of a `.txt` on the Acer is covered by the existing
+  #103 HARDWARE-QUEUE entry (now expects Text Editor for text files). Opting
+  out of *both* vscode and Text Editor still leaves no handler — that is the
+  delete-the-line convention, not a silent live-ISO bug.
+- **Next suggestion:** #95 (Ghostty does not open) or #94 residual
+  (test-install chromium launch).
+
 ## 2026-07-14 — #118: smartd self-gates; the doctor was right all along (this commit)
 - **Task:** BACKLOG #118 — Bernardo's live ISO showed a red Waybar health icon
   reporting smartd.

docs/ROADMAP.md

@@ -380,8 +380,8 @@ Design/decision records and a running log of shipped work (items marked
   the thing a user judges the distro by *before* installing, and what they
   boot to rescue a machine that will not start; it could do neither. The live
   HM user in `flake.nix` now names its own set: **Chromium, libreoffice-fresh,
-  gnome-text-editor, amberol, snapshot** (Bernardo confirmed the gap on real
+  gnome-text-editor, amberol, mpv (#119), snapshot** (Bernardo confirmed the
-  hardware 2026-07-14).
+  gap on real hardware 2026-07-14).
   **Firefox deliberately excluded** (Bernardo's call): Chromium already owns
   the HTTP mime default and ships in the installed template, so it is the
   browser that matches what a user gets after installing — and it was the one
@@ -404,6 +404,17 @@ Design/decision records and a running log of shipped work (items marked
   decision rather than a drive-by. Proved to fail: dropping snapshot makes it
   name the missing entry. **V3 pending** — that the apps *launch* needs real
   hardware (HARDWARE-QUEUE, Acer M5-481T).
+- ✓ **Mime defaults must name a present .desktop (#119):** same bug class as
+  #94, one key over. `text/plain` pointed at `code.desktop` (vscode), which
+  the live ISO never ships — GIO skips the missing entry and leaves no
+  handler, so a double-clicked `.txt` did nothing. Fix: ordered fallback
+  `code.desktop` → `org.gnome.TextEditor.desktop` (HM/GIO try the next when
+  preferred is missing); live gains `mpv` too (video defaults had the same
+  hole, free via the template pin). Guard extended: every
+  `[Default Applications]` key must have *at least one* listed `.desktop` in
+  the live HM path **or** system path (thunar is system-side) *and* on the
+  default template install — proved to fail when `text/plain` is a vscode
+  singleton. Template still prefers vscode when present.
 - ✓ **smartd self-gates on the hardware (#118):** Bernardo booted the live ISO
   and the Waybar health icon was red. Everything downstream was working
   correctly, which is what made it worth writing down: smartd's config is

flake.nix

@@ -560,23 +560,37 @@
                 touch $out
               '';
 
-          # Live-ISO baseline apps (ROADMAP § live-ISO baseline apps, #103).
+          # Live-ISO baseline apps (ROADMAP § live-ISO baseline apps, #103)
-          # The live session shipped no
+          # plus the mime-default presence guard (#94 / #119). The live
-          # browser and no office for as long as it existed — the thing a user
+          # session shipped no browser and no office for as long as it
-          # judges the distro by before installing, and boots to rescue a dead
+          # existed — the thing a user judges the distro by before installing,
-          # machine. Nothing in a build fails when an app silently leaves the
+          # and boots to rescue a dead machine. Nothing in a build fails when
-          # live profile (it just stops being in the launcher, which is
+          # an app silently leaves the live profile (it just stops being in
-          # invisible until someone boots the ISO on real hardware and looks),
+          # the launcher), and a mime default that names a missing .desktop is
-          # so assert both halves: on PATH *and* a .desktop the launcher can
+          # silently skipped by GIO (no handler at all) — so assert both:
-          # see. Same artifacts the ISO ships, no ISO build.
+          # binaries + launcher entries for the baseline suite, and that
+          # every Default Applications key has at least one listed .desktop
+          # present in the live profile or system path (thunar is system-side).
+          # Same artifacts the ISO ships, no ISO build.
           live-baseline-apps =
             let
               liveHm =
                 self.nixosConfigurations.nomarchy-live.config.home-manager.users.${username};
               gen = liveHm.home.activationPackage;
+              # system.path carries NixOS-side apps (thunar); HM-only
+              # home-path does not. A mime default that only names a
+              # system desktop must still resolve.
+              sysPath =
+                self.nixosConfigurations.nomarchy-live.config.system.path;
+              # Template install path: same mime defaults, different package
+              # set (vscode present, gnome-text-editor not). Guard both so
+              # a live-only fix cannot re-break the installed machine.
+              templateGen = downstream.homeConfigurations.me.activationPackage;
+              templateSys =
+                downstream.nixosConfigurations.default.config.system.path;
             in
             pkgs.runCommand "nomarchy-live-baseline-apps"
-              { nativeBuildInputs = [ pkgs.gnugrep pkgs.findutils ]; }
+              { nativeBuildInputs = [ pkgs.gnugrep pkgs.findutils pkgs.python3 ]; }
               ''
                 set -euo pipefail
                 apps=${gen}/home-path/share/applications
@@ -590,11 +604,12 @@
                          impress.desktop \
                          org.gnome.TextEditor.desktop \
                          io.bassi.Amberol.desktop \
+                         mpv.desktop \
                          org.gnome.Snapshot.desktop; do
                   test -f "$apps/$d" || { echo "live-baseline-apps: MISSING launcher entry $d"; exit 1; }
                 done
 
-                for b in chromium libreoffice gnome-text-editor amberol snapshot; do
+                for b in chromium libreoffice gnome-text-editor amberol mpv snapshot; do
                   test -x "$bins/$b" || { echo "live-baseline-apps: MISSING binary $b"; exit 1; }
                 done
 
@@ -603,16 +618,67 @@
                 # so GIO silently skipped the entry and the live session had
                 # no default browser at all).
                 mimes=${gen}/home-files/.config/mimeapps.list
-                grep -q '^x-scheme-handler/https=chromium-browser.desktop' "$mimes"
+                grep -q '^x-scheme-handler/https=chromium-browser.desktop' "$mimes" \
+                  || { echo "live-baseline-apps: https mime must name chromium-browser.desktop (#94)"; exit 1; }
                 test -f "$apps/chromium-browser.desktop"
 
+                # text/plain must prefer vscode but fall through to the live
+                # editor (#119) — never a singleton that only names code.
+                grep -qE '^text/plain=.*org\.gnome\.TextEditor\.desktop' "$mimes" \
+                  || { echo "live-baseline-apps: text/plain must fall through to org.gnome.TextEditor.desktop (#119)"; exit 1; }
+                test -f "$apps/org.gnome.TextEditor.desktop"
+
+                # Every Default Applications key: at least one listed
+                # .desktop must exist in home-path OR system path. A key
+                # whose every entry is missing is the #94/#119 bug class.
+                # Covers live *and* the default template install.
+                python3 - "$mimes" "$apps" "${sysPath}/share/applications" \
+                         "${templateGen}/home-files/.config/mimeapps.list" \
+                         "${templateGen}/home-path/share/applications" \
+                         "${templateSys}/share/applications" <<'PY'
+                import sys
+                from pathlib import Path
+
+                def check(label, mimes, *app_dirs):
+                    text = Path(mimes).read_text()
+                    in_defaults = False
+                    bad = []
+                    for line in text.splitlines():
+                        if line.startswith("["):
+                            in_defaults = line.strip() == "[Default Applications]"
+                            continue
+                        if not in_defaults or not line.strip() or line.startswith("#"):
+                            continue
+                        if "=" not in line:
+                            continue
+                        key, val = line.split("=", 1)
+                        desktops = [d for d in val.split(";") if d.strip()]
+                        if not desktops:
+                            bad.append(f"{key}= (empty)")
+                            continue
+                        if not any(
+                            any((Path(d) / desk).is_file() for d in app_dirs)
+                            for desk in desktops
+                        ):
+                            bad.append(f"{key}={';'.join(desktops)} (none present)")
+                    if bad:
+                        print(f"live-baseline-apps: mime defaults missing on {label}:")
+                        for b in bad:
+                            print(f"  {b}")
+                        sys.exit(1)
+                    print(f"live-baseline-apps: mime defaults ok on {label}")
+
+                check("live", sys.argv[1], sys.argv[2], sys.argv[3])
+                check("template", sys.argv[4], sys.argv[5], sys.argv[6])
+                PY
+
                 # Firefox is deliberately absent — a second browser is the one
                 # item in #103's list that costs a real closure, and chromium
                 # owns the mime default (Bernardo 2026-07-14). If it ever
                 # ships here, that is a size decision, not a drive-by.
                 test ! -f "$apps/firefox.desktop" || { echo "live-baseline-apps: firefox reappeared — size decision, see #103"; exit 1; }
 
-                echo "live-baseline-apps: ok — browser, office, editor, music, camera on PATH + in the launcher"
+                echo "live-baseline-apps: ok — browser, office, editor, music, video, camera + mime defaults resolve"
                 touch $out
               '';
 
@@ -1919,6 +1985,8 @@
                   libreoffice-fresh   # documents/sheets/slides off a dying disk
                   gnome-text-editor   # the maintained gedit successor
                   amberol             # music player (also in the template)
+                  mpv                 # video (mime defaults → mpv.desktop; also
+                                      # template — free on the ISO via the pin)
                   snapshot            # camera — the maintained Cheese successor
                 ];
               };

modules/home/mime.nix

@@ -44,8 +44,12 @@ lib.mkIf config.nomarchy.mime.enable {
       "audio/x-m4a" = "io.bassi.Amberol.desktop";
       "audio/aac" = "io.bassi.Amberol.desktop";
 
-      # The template's active editor; degrades if you drop vscode.
+      # Prefer the template's vscode; fall through to gnome-text-editor
-      "text/plain" = "code.desktop";
+      # (ships on the live ISO after #103, and is the only editor there).
+      # A singleton that names an absent .desktop is silently skipped by
+      # GIO and leaves no handler at all — the #94 / #119 trap. HM tries
+      # the next entry when the preferred one is missing.
+      "text/plain" = [ "code.desktop" "org.gnome.TextEditor.desktop" ];
 
       # The system-side Thunar (nomarchy.system.fileManager).
       "inode/directory" = "thunar.desktop";