diff --git a/SPECGAPS.md b/SPECGAPS.md
index 03231c8..6a12a7a 100644
--- a/SPECGAPS.md
+++ b/SPECGAPS.md
@@ -61,7 +61,7 @@ Gap categories: **SC** = spec correct, fix code | **CS** = code correct, update
 | ID | Behavior | Code Location | Path |
 |---|---|---|---|
 | ~~B1-1~~ | ~~Chat inline surfaces (9 types: card, chart, form, list, metric, mindmap, table, tabs, text/json)~~ | `tool_surfaces.ex` | **Resolved:** added InlineSurface value type with all 9 discriminators, supporting value types (SurfaceAction, ChartSeries, MindmapNode, FormField, FieldOption, TabPanel), inline_surfaces on ChatMessage, InlineSurfaceRendering guarantee, and surface_form_debounce_ms config to editor_chat.allium; updated StructuredRenderTools invariant in ai.allium to list all 9 types |
-| B1-2 | Auto-translation system (AutoTranslation.maybe_schedule, media cascade, batch fill) | `lib/bds/posts/auto_translation.ex` | Distill into spec |
+| ~~B1-2~~ | ~~Auto-translation system (AutoTranslation.maybe_schedule, media cascade, batch fill)~~ | `lib/bds/posts/auto_translation.ex` | **Resolved:** distilled into translation.allium — added `AutoTranslationControlSurface` (PostSavedForAutoTranslation reactive + FillMissingTranslationsRequested batch triggers), three rules (`ScheduleAutoTranslation` draft-per-missing-language + media cascade, `AutoTranslatePost` upsert/auto-publish primitive, `AutoTranslateMediaCascade` linked-media per-language tasks, `FillMissingTranslations` published-only batch emitting `ProgressReported` + `FillMissingTranslationsCompleted`), three invariants (`AutoTranslationGatedByEndpoint`, `AutoTranslationSkipsDoNotTranslate`, `AutoTranslationOnlyMissingLanguages`), and `auto_translation_task_group_name` config; `allium check` passes |
 | B1-3 | 3 extra settings sections (Technology, MCP, Data Maintenance) | `lib/bds/ui/settings_editor/` | Distill into spec |
 | B1-4 | Style/Theme as separate tab (`:style`), not settings section | `lib/bds/ui/style_editor.ex` | Distill into spec |
 | B1-5 | `published_*` snapshot fields on Post for diffing | `lib/bds/posts/post.ex:61-65` | Add to post.allium entity |
@@ -193,7 +193,7 @@ All reconciled to follow code. Specs must be self-consistent and match code.
 1c. ~~**A1-17**~~ — blogmark deep-link handler resolved: `BDS.Desktop.DeepLink` receives OS `bds2://` URL events and `BDS.Blogmark` parses them, runs the transform pipeline, and creates+opens a draft post (macOS `Info.plist` scheme registration documented, pending an app-bundle pipeline)
 2. **D1-1 through D1-18** — untested invariants/guarantees
 3. **C-1 through C-3** — internal spec inconsistencies (reconcile to code)
-4. **B1-1 through B1-6** — major code behaviors missing from spec
+4. **B1-1 through B1-6** — major code behaviors missing from spec (B1-1, B1-2 resolved)
 5. **A2-1 through A2-17** — spec drift (code is normative, update spec)
 6. **D2-1 through D2-17** — untested rules
 7. **D3-1 through D3-11** — partial test coverage
diff --git a/specs/translation.allium b/specs/translation.allium
index a4a168f..a21b0f4 100644
--- a/specs/translation.allium
+++ b/specs/translation.allium
@@ -186,3 +186,128 @@ invariant FtsIncludesTranslations {
         for t in post.translations:
             includes_text(search_index(post), t.title)
 }
+
+-- ===========================================================================
+-- Auto-Translation System
+-- Distilled from: lib/bds/posts/auto_translation.ex
+--
+-- Two entry points share one translation primitive:
+--   1. ScheduleAutoTranslation - reactive, fired after a post is created or
+--      updated. One background task per missing language produces a DRAFT
+--      translation, then cascades to the post's linked media.
+--   2. FillMissingTranslations - batch maintenance action. Scans every
+--      published post, AUTO-PUBLISHES the generated translations, fills linked
+--      media, reports progress and returns a summary.
+-- All AI work is gated by a resolvable endpoint and runs on background tasks.
+-- ===========================================================================
+
+config {
+    -- Background translations use the "AI" task group named per project.
+    auto_translation_task_group_name: String = "AI"
+}
+
+surface AutoTranslationControlSurface {
+    facing _: TranslationOperator
+
+    provides:
+        -- Reactive trigger: emitted by post create/update side effects.
+        PostSavedForAutoTranslation(post)
+        -- Batch trigger: "fill missing translations" maintenance action.
+        FillMissingTranslationsRequested(project)
+}
+
+invariant AutoTranslationGatedByEndpoint {
+    -- No automatic translation runs unless an endpoint is resolvable for the
+    -- current mode. Airplane mode needs url+model; online additionally needs an
+    -- api_key. When unconfigured, scheduling is a silent no-op.
+    -- See ai.allium AirplaneModeGating for endpoint selection.
+    for post in Posts:
+        auto_translation_runs(post) implies endpoint_configured(post.project)
+}
+
+invariant AutoTranslationSkipsDoNotTranslate {
+    -- Posts flagged do_not_translate never schedule background translation,
+    -- and the batch scan rejects them before computing missing languages.
+    for post in Posts where post.do_not_translate:
+        not auto_translation_runs(post)
+}
+
+invariant AutoTranslationOnlyMissingLanguages {
+    -- The target set is the configured languages (main_language plus
+    -- blog_languages, normalized + de-duplicated) minus the post's source
+    -- language and any language that already has a translation.
+    for post in Posts:
+        auto_translation_targets(post) =
+            configured_languages(post.project)
+                - source_language(post)
+                - post.available_languages
+}
+
+rule ScheduleAutoTranslation {
+    when: PostSavedForAutoTranslation(post)
+    requires: not post.do_not_translate
+    requires: endpoint_configured(post.project)
+    -- One background task per missing language, each producing a DRAFT
+    -- translation (not auto-published) followed by a media cascade.
+    for language in auto_translation_targets(post):
+        ensures: BackgroundTaskSubmitted(
+            group: post.project,
+            group_name: config.auto_translation_task_group_name)
+        ensures: AutoTranslatePost(post, language, auto_publish: false)
+        ensures: AutoTranslateMediaCascade(post, language)
+
+    @guidance
+        -- Best-effort: missing metadata, unconfigured endpoint, or
+        -- do_not_translate all collapse to a silent success with no task.
+}
+
+rule AutoTranslatePost {
+    when: AutoTranslatePost(post, language, auto_publish)
+    requires: trim(editor_body(post)) != ""
+    -- Calls the AI endpoint with the post's source language, then upserts a
+    -- translation marked auto_generated. Publishes only in the batch path.
+    ensures:
+        let translation = UpsertPostTranslation(post, language)
+        if auto_publish:
+            translation.status = published
+        else:
+            translation.status = draft
+
+    @guidance
+        -- An empty body yields a no_content_to_translate error and no
+        -- translation is created.
+}
+
+rule AutoTranslateMediaCascade {
+    when: AutoTranslateMediaCascade(post, language)
+    -- After a post translation, each linked media (ordered by sort_order) gets
+    -- its own background task when its source language differs from the target
+    -- and it lacks a translation in that language.
+    for m in post.linked_media:
+        if m.language != "" and m.language != language and not (language in m.available_languages):
+            ensures: BackgroundTaskSubmitted(
+                group: post.project,
+                group_name: config.auto_translation_task_group_name)
+            ensures: media/UpsertMediaTranslation(m, language)
+}
+
+rule FillMissingTranslations {
+    when: FillMissingTranslationsRequested(project)
+    -- Batch maintenance. No-op (nothing_to_do) when there is at most one
+    -- configured language or nothing is missing. Otherwise scans published,
+    -- non-do_not_translate posts and their linked media.
+    requires: configured_languages(project).count > 1
+    for post in project.posts where status = published and not do_not_translate:
+        for language in auto_translation_targets(post):
+            ensures: AutoTranslatePost(post, language, auto_publish: true)
+            ensures: AutoTranslateMediaCascade(post, language)
+    ensures: ProgressReported(project)
+    ensures: FillMissingTranslationsCompleted(project)
+
+    @guidance
+        -- Returns a summary of counts: translated_posts, translated_media,
+        -- failed_count, warned_count, and nothing_to_do. nothing_to_do is true
+        -- when there is at most one configured language or nothing is missing.
+        -- Per-item failures increment failed_count and never abort the batch.
+        -- Progress runs through scanning (0.0-0.15) then per-item (0.15-1.0).
+}