diff --git a/src/core/SaveData.lua b/src/core/SaveData.lua
index d5e20f2b..004c5bfa 100644
--- a/src/core/SaveData.lua
+++ b/src/core/SaveData.lua
@@ -672,12 +672,10 @@ function SaveData.defaultOptions()
     -- GitHub release checks for mods with a manifest "github" field
     -- (src/mods/ModUpdate.lua). Keyed by owner/repo; TTL is six hours.
     modUpdateCache = {},
-    -- Community mod indexes the player has chosen to browse
-    -- (src/mods/ModIndex.lua), in the order they added them.  Empty by
-    -- default and never populated automatically: adding an index is how a
-    -- player says they trust whoever publishes it, so the launcher asks
-    -- rather than shipping one.  Rows are { url, feed, base, fallback,
-    -- label }.
+    -- Player-added mod indexes, in their chosen order.  ModIndex.sources()
+    -- includes the permanent main index alongside these and reuses any
+    -- main-index row saved by an older launcher.  Rows are
+    -- { url, feed, base, fallback, label }.
     modIndexes = {},
     -- Parsed index listings keyed by feed URL; TTL is 24 hours, matching how
     -- often the feeds themselves rebuild.
diff --git a/src/import/LauncherView.lua b/src/import/LauncherView.lua
index 6536c606..9b577a46 100644
--- a/src/import/LauncherView.lua
+++ b/src/import/LauncherView.lua
@@ -5005,10 +5005,11 @@ local function buildFilterModal(imp, m)
       action = function() imp._filterPopup = nil end })
 end
 
--- Index manager: every source with its Remove, plus Add and Refresh all.
+-- Index manager: built-in source and removable additions, plus Add and Refresh all.
 -- This replaces both the old always-visible source rows above the search
 -- field and the lone "Add index" header button.
 local function buildIndexesModal(imp, m)
+  local ModIndex = require("src.mods.ModIndex")
   local sources = imp.findSources or {}
   local pad = math.floor(18 * m.s)
   local w = math.floor(520 * m.s)
@@ -5031,17 +5032,24 @@ local function buildIndexesModal(imp, m)
   else
     for i, source in ipairs(sources) do
       local feed = source.feed
+      local builtIn = ModIndex.isBuiltIn(feed)
+      local actionLabel = builtIn and Strings("Built-in") or Strings("Remove")
       local id = "idx-rm-" .. tostring(feed)
       local cy = place(id, (i - 1) * (rowH + gap), rowH)
-      local rmW = Kit.textWidth("small", Strings("Remove"))
+      local rmW = Kit.textWidth("small", actionLabel)
         + math.floor(20 * m.s)
       Kit.text("small", Kit.ellipsize("small", source.label or feed,
         rw - rmW - math.floor(12 * m.s)), x,
         cy + (rowH - Kit.textHeight("small")) / 2, PAL.detail)
-      btn(imp, x + rw - rmW, cy, rmW, rowH,
-        id, Strings("Remove"), {
-          kind = "danger", font = "small",
-          action = function() imp:_removeIndex(feed) end })
+      if builtIn then
+        Kit.text("small", actionLabel, x + rw - rmW,
+          cy + (rowH - Kit.textHeight("small")) / 2, PAL.muted)
+      else
+        btn(imp, x + rw - rmW, cy, rmW, rowH,
+          id, actionLabel, {
+            kind = "danger", font = "small",
+            action = function() imp:_removeIndex(feed) end })
+      end
     end
   end
   btn(imp, x, place("idx-add", addY, m.btnH), rw, m.btnH, "idx-add",
diff --git a/src/import/RomImporter.lua b/src/import/RomImporter.lua
index 626bc4c8..9ef3002f 100644
--- a/src/import/RomImporter.lua
+++ b/src/import/RomImporter.lua
@@ -8032,10 +8032,8 @@ end
 --
 -- The index is metadata only (src/mods/ModIndex.lua): it says where a mod's
 -- zip lives, and the install runs through exactly the same path "Import mod
--- .zip" does.  Nothing here is automatic -- no index ships with the launcher,
--- and the tab stays an empty "Add an index" prompt until the player names one,
--- because subscribing to somebody's list of mods is a trust decision and not a
--- default.
+-- .zip" does.  The main index is included by default; players can add other
+-- indexes alongside it.  Installing a listed mod remains an explicit action.
 --
 -- Fetching is the same synchronous curl the update checks already use, cached
 -- in options for a day, so the first open of the tab costs one round trip and
@@ -8556,9 +8554,7 @@ function RomImporter:_pumpFindStats()
   if next(pending) == nil then self._findStatsPending = nil end
 end
 
--- Open the "add an index" text prompt.  Deliberately a typed URL rather than a
--- picked-from-a-list affair: there is no blessed index, and presenting one
--- would make the launcher's choice look like an endorsement.
+-- Open the text prompt for an additional index URL.
 function RomImporter:_promptAddIndex()
   self._indexPrompt = { text = "" }
   self:_armTextInput()
diff --git a/src/mods/ModIndex.lua b/src/mods/ModIndex.lua
index 7208d48d..48f7f5ea 100644
--- a/src/mods/ModIndex.lua
+++ b/src/mods/ModIndex.lua
@@ -11,9 +11,8 @@
 -- no network) so the engine tier can table-drive it, and the fetch/cache half
 -- reaches for curl and options.lua.
 --
--- Sources are never added automatically.  options.modIndexes is a player-built
--- list -- adding an index is a deliberate act of trusting whoever publishes it,
--- so the launcher ships with none and asks.
+-- The main index is built in and cannot be removed.  options.modIndexes keeps
+-- player-added sources, including main-index rows saved by older launchers.
 --
 -- schema_version is a hard gate, not a hint: a bumped feed may reuse a field
 -- name for something else, so an unknown version is refused outright rather
@@ -637,18 +636,34 @@ local function loadOptions()
   return require("src.core.SaveData").loadOptions()
 end
 
--- The player's index list, normalised.  Rows are { url, feed, base, fallback,
+local BUILTIN = ModIndex.resolveSource("bryanthaboi/gen1recomp-mod-index")
+BUILTIN.url = "bryanthaboi/gen1recomp-mod-index"
+
+function ModIndex.isBuiltIn(feed)
+  return feed == BUILTIN.feed
+end
+
+-- The player's index list plus the built-in source.  Rows are { url, feed, base, fallback,
 -- label }; `url` is what they typed, kept so the row reads back the way they
--- entered it.
+-- entered it.  Keep an existing main-index row in place to preserve source
+-- precedence and its cache; otherwise append it without rewriting options.
 function ModIndex.sources()
   local ok, opts = pcall(loadOptions)
-  if not ok or type(opts) ~= "table" then return {} end
-  local out = {}
-  for _, row in ipairs(opts.modIndexes or {}) do
+  local saved = ok and type(opts) == "table" and opts.modIndexes or {}
+  local out, hasBuiltin = {}, false
+  for _, row in ipairs(type(saved) == "table" and saved or {}) do
     if type(row) == "table" and type(row.feed) == "string" then
-      out[#out + 1] = row
+      if not ModIndex.isBuiltIn(row.feed) or not hasBuiltin then
+        out[#out + 1] = row
+      end
+      if ModIndex.isBuiltIn(row.feed) then hasBuiltin = true end
     end
   end
+  if not hasBuiltin then
+    local row = {}
+    for k, v in pairs(BUILTIN) do row[k] = v end
+    out[#out + 1] = row
+  end
   return out
 end
 
@@ -657,6 +672,7 @@ end
 function ModIndex.addSource(input)
   local source, err = ModIndex.resolveSource(input)
   if not source then return nil, err end
+  if ModIndex.isBuiltIn(source.feed) then return nil, "that index is already added" end
   local ok, result, addErr = pcall(function()
     local SaveData = require("src.core.SaveData")
     local opts = loadOptions()
@@ -680,6 +696,7 @@ end
 -- outlives the index it came from.
 function ModIndex.removeSource(feed)
   if type(feed) ~= "string" or feed == "" then return nil, "missing index" end
+  if ModIndex.isBuiltIn(feed) then return nil, "the built-in index cannot be removed" end
   local ok, result = pcall(function()
     local SaveData = require("src.core.SaveData")
     local opts = loadOptions()
diff --git a/tests/engine/cart_launcher.lua b/tests/engine/cart_launcher.lua
index 9c21701f..15956e13 100644
--- a/tests/engine/cart_launcher.lua
+++ b/tests/engine/cart_launcher.lua
@@ -1229,6 +1229,7 @@ check(find.findBase == nil, "with no base-game filter armed")
 find.tab = "find"
 find.modScope = nil
 find.findLoaded = true
+find._findFetch = nil
 find.findSources = { { feed = "https://example.test/data/index.json",
                        base = "https://example.test/",
                        label = "example/index" } }
diff --git a/tests/engine/launcher_modal_scroll_2437.lua b/tests/engine/launcher_modal_scroll_2437.lua
index 0a19617a..c371e1a6 100644
--- a/tests/engine/launcher_modal_scroll_2437.lua
+++ b/tests/engine/launcher_modal_scroll_2437.lua
@@ -8,6 +8,7 @@ local View = require("src.import.LauncherView")
 local Transition = require("src.ui.kit.Transition")
 local Importer = require("src.import.RomImporter")
 local GameVersion = require("src.core.GameVersion")
+local ModIndex = require("src.mods.ModIndex")
 
 local width, height = 853, 480
 love.graphics.getDimensions = function() return width, height end
@@ -23,6 +24,7 @@ local function fixture(tab)
   local imp = Importer.new(function() end, { launcher = true, onEditSave = function() end })
   for _, v in ipairs(GameVersion.ORDER) do imp.ready[v] = true end
   imp._ensureSlots, imp._ensureMods = function() end, function() end
+  imp._ensureFind = function() end
   imp._refreshMods = function() end
   imp._resetModOrder = function(self) self.didReset = true end
   imp.mods = {}
@@ -44,6 +46,7 @@ local MODALS = {
     open = function(imp)
       imp.findSources = {}
       for i = 1, 6 do imp.findSources[i] = { feed = "https://x/" .. i, label = "Index " .. i } end
+      imp.findSources[1] = ModIndex.resolveSource("bryanthaboi/gen1recomp-mod-index")
       imp._indexManage = true
     end },
 }
@@ -85,7 +88,9 @@ for _, size in ipairs({ { 853, 480 }, { 780, 360 }, { 1280, 720 } }) do
     local state = imp._modalScroll and imp._modalScroll[spec.key]
     T.check(state ~= nil and state.rect ~= nil, tag .. " records a scroll rect")
     local closeSeen, escaped = false, {}
+    local removes = 0
     for _, r in ipairs(rects) do
+      if r.label == "Remove" then removes = removes + 1 end
       if r.clip then
         if not inside(r.clip, width, height) then escaped[#escaped + 1] = r.label .. " clip" end
         if state and not within(r.clip, state.rect) then escaped[#escaped + 1] = r.label .. " clip outside body" end
@@ -98,6 +103,9 @@ for _, size in ipairs({ { 853, 480 }, { 780, 360 }, { 1280, 720 } }) do
       end
     end
     T.check(closeSeen, tag .. " draws a pinned Close")
+    if spec.key == "_indexManage" then
+      T.eq(removes, 5, tag .. " only offers Remove for the five custom indexes")
+    end
     T.check(#escaped == 0, tag .. " keeps every control on screen or in the scroll clip: "
       .. table.concat(escaped, ", "))
     if state and state.rect then
diff --git a/tests/engine/launcher_update_all.lua b/tests/engine/launcher_update_all.lua
index f72de42e..d6cc0804 100644
--- a/tests/engine/launcher_update_all.lua
+++ b/tests/engine/launcher_update_all.lua
@@ -108,6 +108,7 @@ local function launcher(secondStatus, feedCarts)
     findIndex = { mods = {}, carts = feedCarts or {} },
   }, RomImporter)
   ri._refreshMods = function() end
+  ri._refreshFindSources = function(self) self.findSources = {} end
   return ri
 end
 
diff --git a/tests/engine/mod_index_tests.lua b/tests/engine/mod_index_tests.lua
index 8d30f22b..6d509ff8 100644
--- a/tests/engine/mod_index_tests.lua
+++ b/tests/engine/mod_index_tests.lua
@@ -48,6 +48,66 @@ do
   check(bad == nil and err ~= nil, "nil input soft-fails")
 end
 
+-- ------- permanent main source, including options saved before it was built in
+
+do
+  local oldSaveData = package.loaded["src.core.SaveData"]
+  local opts, writes = {}, 0
+  package.loaded["src.core.SaveData"] = {
+    loadOptions = function() return opts end,
+    saveOptions = function(saved) opts = saved; writes = writes + 1; return saved end,
+  }
+  local main = ModIndex.resolveSource("bryanthaboi/gen1recomp-mod-index")
+  local custom = ModIndex.resolveSource("other/community-index")
+  local cached = { checkedAt = 123, mods = { { id = "existing" } } }
+
+  local sources = ModIndex.sources()
+  eq(#sources, 1, "fresh options include the main index")
+  eq(sources[1].feed, main.feed, "the default uses the main feed")
+  eq(sources[1].fallback, main.fallback, "the default includes the raw fallback")
+  sources[1].feed = "changed by caller"
+  eq(ModIndex.sources()[1].feed, main.feed, "callers cannot alter the built-in definition")
+  eq(writes, 0, "reading sources does not rewrite options")
+
+  for _, url in ipairs({ "bryanthaboi/gen1recomp-mod-index",
+      "https://github.com/bryanthaboi/gen1recomp-mod-index",
+      main.base, main.base:sub(1, -2), main.feed }) do
+    local savedMain = ModIndex.resolveSource(url)
+    savedMain.url = url
+    opts = { modIndexes = { custom, savedMain, main },
+      modIndexCache = { [main.feed] = cached } }
+    sources = ModIndex.sources()
+    eq(#sources, 2, "an already-added main index is listed once: " .. url)
+    eq(sources[1], custom, "the existing source precedence is preserved")
+    eq(sources[2], savedMain, "the first saved main-index row is reused")
+    eq(sources[2].url, url, "the player's original URL is preserved")
+    eq(ModIndex.readCache(main.feed), cached, "the existing main-index cache survives")
+    local added, addErr = ModIndex.addSource(url)
+    check(added == nil and addErr ~= nil, "the built-in source cannot be added again")
+    local removed, removeErr = ModIndex.removeSource(main.feed)
+    check(removed == nil and removeErr ~= nil, "an older main-index row cannot be removed")
+    eq(opts.modIndexCache[main.feed], cached, "blocked removal keeps its cache")
+  end
+  eq(writes, 0, "duplicate additions and blocked removals do not write options")
+
+  opts = { modIndexes = { custom }, modIndexCache = { [custom.feed] = cached } }
+  sources = ModIndex.sources()
+  eq(#sources, 2, "existing custom-only options gain the default")
+  eq(sources[1], custom, "adding the default preserves custom-source precedence")
+  eq(sources[2].feed, main.feed, "the missing main source is appended")
+  check(ModIndex.isBuiltIn(main.feed), "the main index is protected")
+  check(not ModIndex.isBuiltIn(custom.feed), "a custom index remains removable")
+  check(ModIndex.removeSource(custom.feed), "a custom source can still be removed")
+  eq(opts.modIndexCache[custom.feed], nil, "custom-source removal clears its cache")
+  eq(#ModIndex.sources(), 1, "removing the last custom source leaves the main index")
+  check(ModIndex.addSource("other/community-index") ~= nil, "custom sources can still be added")
+  eq(#ModIndex.sources(), 2, "the added custom source appears beside the main index")
+
+  package.loaded["src.core.SaveData"].loadOptions = function() error("unavailable options") end
+  eq(ModIndex.sources()[1].feed, main.feed, "the main index remains available if options cannot load")
+  package.loaded["src.core.SaveData"] = oldSaveData
+end
+
 do
   local base = "https://bryanthaboi.github.io/gen1recomp-mod-index/"
   eq(ModIndex.joinUrl(base, "data/mods/bryanthaboi@nuzlocke/thumbnail.png"),
@@ -351,6 +411,20 @@ end
 
 -- ------- search / filter
 
+do
+  local index = ModIndex.parse(feed({
+    { id = "untamed_advanced", title = "Untamed Advanced",
+      games = { "firered", "leafgreen", "emerald" }, categories = { "GAMEPLAY" } },
+  }))
+  for _, game in ipairs({ "gen3", "firered", "leafgreen", "emerald" }) do
+    local rows = ModIndex.filter(index.mods, { game = game, query = "untamed" })
+    eq(#rows, 1, "Untamed Advanced appears when filtering by " .. game)
+    eq(rows[1] and rows[1].id, "untamed_advanced", "the filtered listing is Untamed Advanced")
+  end
+  eq(#ModIndex.filter(index.mods, { game = "gen2", query = "untamed" }), 0,
+    "Untamed Advanced remains excluded from unsupported generations")
+end
+
 do
   local mods = {
     { id = "nuzlocke", title = "Nuzlocke", author = "bryanthaboi",
@@ -613,4 +687,4 @@ do
     "a cartless feed offers no base games")
 end
 
-print("ok mod_index_tests")
+T.finish("mod index")