# bDS2 Elixir Anti-Pattern & Best-Practice Audit

> Audited: 2026-05-06
> Scope: Elixir application, Phoenix LiveView UI, Ecto DB layer, Desktop (wx) integration, Rendering/Generation pipelines

---

## How to use this file

1. Pick a section.
2. Search the codebase for the file/line references.
3. Write a failing test that reproduces the issue.
4. Fix the code.
5. Run the full test suite and `mix dialyzer`.
6. Delete the item from this file.

---

## Critical (Fix Immediately)

### ~~CSM-001 — Atom Table Exhaustion Vulnerability~~ ✅ FIXED
- **Fixed:** 2026-05-06
- **What was done:**
  - Added `BDS.MapUtils.safe_atomize_key/1` and `BDS.MapUtils.safe_atomize_keys/1` — uses `String.to_existing_atom/1` with rescue fallback to keep unknown keys as strings.
  - Replaced all 6 affected `String.to_atom` call sites:
    - `lib/bds/import_definitions.ex` — `atomize_keys/1` → `MapUtils.safe_atomize_keys/1`
    - `lib/bds/import_execution.ex` — `normalize_report/1` → `MapUtils.safe_atomize_keys/1`
    - `lib/bds/ai/catalog.ex` — `atomize_map_keys/1` → `MapUtils.safe_atomize_keys/1`, `parse_modality/1` → `MapUtils.safe_atomize_key/1`
    - `lib/bds/ai/chat_tools.ex` — `metadata_attrs/2` → `MapUtils.safe_atomize_key/1`
    - `lib/bds/desktop/automation.ex` — `atomize_map/1` → `MapUtils.safe_atomize_keys/1`
  - Replaced lower-risk `String.to_atom` with `String.to_existing_atom/1`:
    - `lib/bds/ui/menu_bar.ex` — sidebar view and singleton editor command IDs
    - `lib/bds/ui/workbench.ex` — `normalize_type/1`
    - `lib/bds/desktop/shell_live/chat_editor/tool_surfaces.ex` — `map_value/3`
    - `lib/bds/release_packaging.ex` — `normalize_platform/1`
  - Updated `test/bds/bounded_atoms_test.exs` to enforce no `String.to_atom` on dynamic data (replaced old `String.to_existing_atom` ban).

---

### ~~CSM-002 — Search Loads Entire Tables into Memory~~ ✅ FIXED
- **Fixed:** 2026-05-07
- **What was done:**
  - Replaced `search_posts/3` and `search_media/3` with SQL-level filtering and pagination.
  - Blank queries now use pure Ecto queries with `where` clauses for status, language, year/month, date range, tags, categories, and missing translations.
  - Non-blank (FTS) queries use a CTE (`WITH fts_results AS (...)`) to preserve `bm25` ordering, joined with the posts/media table, with all filters applied in SQL.
  - Tag and category overlap filtering uses `json_each` in `EXISTS` subqueries.
  - Missing-translation filtering uses a `NOT EXISTS` correlated subquery.
  - Count uses `select count` + `Repo.one` instead of `length(all_records)`.
  - Pagination uses SQL `LIMIT`/`OFFSET` instead of `Enum.drop`/`Enum.take`.
  - Removed all old Elixir-side filter helpers: `candidate_post_ids`, `load_posts_in_order`, `filter_posts`, `paginate`, `matches_status?`, `matches_overlap?`, etc.
  - Added comprehensive tests for blank-query and non-blank-query filtering across all filter dimensions.

---

### ~~CSM-003 — Non-Atomic Side Effects in Post CRUD~~ ✅ FIXED
- **Fixed:** 2026-05-07
- **What was done:**
  - Replaced all 11 `Repo.delete!` call sites with `Repo.delete` + `{:error, _}` handling:
    - `lib/bds/posts.ex` — `delete_post/1`
    - `lib/bds/scripts.ex` — `delete_script/1`
    - `lib/bds/media.ex` — `delete_media/1`, `delete_media_translation/3`
    - `lib/bds/templates.ex` — `delete_template/2`, `remove_orphan_templates/2`
    - `lib/bds/tags.ex` — `delete_tag/1`, `merge_tags/2`
    - `lib/bds/projects.ex` — `delete_project/1`
    - `lib/bds/posts/translations.ex` — `delete_post_translation/1`
    - `lib/bds/posts/translation_validation.ex` — `fix_invalid_database_row/1`
  - Reordered `delete_post/1` to perform `Repo.delete` first, then clean up files/embeddings/search/links. Side effects now only run after DB commit succeeds.
  - Same reordering applied to `delete_script/1`, `delete_media/1`, `delete_template/2`, and `delete_post_translation/1`.
  - `delete_media/1` now wraps translation + media deletes in a `Repo.transaction` for atomicity.
  - Tags and projects already used `Repo.transaction`; replaced inner `Repo.delete!` with `Repo.delete` + `Repo.rollback` on error.
  - Added tests for delete atomicity and not-found handling.

---

### CSM-004 — Blocking `init/1` + Missing `terminate/2` in Job Runner
- **File:** `lib/bds/scripting/job_runner.ex:28-35`
- **What:**
  1. Synchronous `GenServer.call` to `JobStore.attach_runner/2` inside `init/1` (Z. 30) blocks the supervisor if `JobStore` is slow.
  2. `Process.flag(:trap_exit, true)` (Z. 29) is set but there is **no** `terminate/2` callback and **no** `{:EXIT, ...}` handler in `handle_info`.
- **Why it's bad:**
  - Supervisor child startup hangs if `JobStore` is slow or unavailable.
  - If the runner process is killed (not via `:cancel`), the PID leaks in `JobStore.runners`. The `detach_runner/2` call only happens in `handle_call(:cancel)` (Z. 71) and `handle_info({ref, result})` (Z. 95) and `handle_info({:DOWN, ...})` (Z. 117). A linked process crash with `trap_exit` would send `{:EXIT, pid, reason}` which has **no handler**, so the runner stops without detaching.
- **Fix:**
  - Move `attach_runner` to `handle_continue/2`.
  - Either remove `trap_exit` (the task uses `async_nolink`, so links aren't the issue) OR add `terminate/2` that calls `JobStore.detach_runner/2` and add an `{:EXIT, ...}` clause in `handle_info`.
- **Test:** Start a runner, kill it (not via cancel); assert `JobStore` does not contain the dead PID.

---

### CSM-005 — Client-Side Filtering of Entire Tables
- **Files:** `lib/bds/ui/sidebar.ex`, `lib/bds/tags.ex`, `lib/bds/ui/dashboard.ex`
- **What:**
  - `UI.Sidebar.list_posts/1` (Z. 464-482) loads every post for a project, then `apply_post_filters/1` (Z. 608-615) filters in Elixir. Translation counts are a separate query but still unbounded.
  - `Tags.posts_with_tag/2` (Z. 310-312) and `Tags.posts_with_any_tag/2` (Z. 314-316) load **all posts** to filter by tag name. `Tags.post_tag_names/1` (Z. 320-322) loads all posts to extract tag names.
  - `UI.Dashboard.snapshot/1` (Z. 14-35) loads ALL posts and ALL media for counts and stats. Post stats (Z. 77-87) and media stats (Z. 89-96) are computed in Elixir via `Enum.reduce`.
  - `Posts.dashboard_stats/1` (posts.ex:374-394) loads all post statuses and counts in Elixir.
- **Fix:**
  - Sidebar: Use `Repo.aggregate` for counts, `where` clauses for filters, `limit`/`offset` for pagination. Preload tag colors separately.
  - Tags: Use `where: fragment("? IN (?)", ^tag_name, post.tags)` or JSON functions. For `post_tag_names`, use `Repo.aggregate` + `distinct`.
  - Dashboard: Use `Repo.aggregate(:count)` with `group_by` for status counts, media counts, tag clouds, and category counts. No need to load full records.
  - `dashboard_stats`: Replace with `from post in Post, where: post.project_id == ^project_id, group_by: post.status, select: {post.status, count(post.id)}`.
- **Test:** Create 10,000 posts; open the sidebar; assert the LiveView process memory stays bounded.

---

## High Severity

### CSM-006 — N+1 Queries in Reindexing & Rendering
- **Files:** `lib/bds/search.ex:166-177`, `lib/bds/rendering/list_archive.ex:181`, `lib/bds/rendering/post_rendering.ex:21`
- **What:**
  - `Search.reindex_posts/1` (Z. 172-177) calls `insert_post_index/1` per post inside `Enum.each`; `insert_post_index` calls `post_index_fields/1` (Z. 268) which calls `post_translations/1` (Z. 494) — one query per post for translations. Same for media reindexing.
  - `ListArchive` (Z. 181) and `PostRendering` (Z. 21) call `load_post_record/1` per-post inside `Enum.map`, which does `Repo.get(Post, post_id)` per iteration.
- **Fix:** Preload all translations in a single query before the loop, or batch-insert with `Repo.insert_all`. For rendering, preload all needed records in one query.
- **Test:** Reindex 100 posts; assert the total query count is <5 (use `Ecto.Adapters.SQL.query!/2` hook or logger capture).

---

### CSM-007 — Monolithic State Rebuild ("God Function")
- **File:** `lib/bds/desktop/shell_live.ex:554-616`
- **What:** `reload_shell/2` rebuilds sidebar, dashboard, git badge, tasks, status bar, tab meta, and panel data on almost every event. This function is called from most `handle_event` and `handle_info` callbacks, even for trivial state changes like sidebar toggle.
- **Why it's bad:** Even a simple sidebar toggle triggers 5+ unrelated DB queries (project_snapshot, dashboard, git_badge_count, sidebar_view, task_status). The sidebar and dashboard data are rebuilt even when only the panel content changed. Output entries and editor meta are recalculated unnecessarily.
- **Fix:** Decompose into focused updaters, each only querying what it needs:
  - `refresh_sidebar/2` — only queries sidebar data
  - `refresh_dashboard/2` — only queries dashboard data
  - `refresh_git_badge/2` — only queries git status
  - `refresh_task_status/2` — only queries task state
  - `refresh_tab_meta/2` — only syncs tab metadata
  Each `handle_event` / `handle_info` should call only the relevant updaters.
- **Test:** Toggle sidebar; assert no dashboard or git queries are executed. Save a post; assert sidebar refreshes but dashboard does not.

---

### CSM-008 — DB Queries During Render Path
- **Files:** `lib/bds/desktop/shell_live/panel_renderer.ex`, `lib/bds/desktop/shell_live/tab_helpers.ex`
- **What:**
  - `panel_renderer.ex:199-209` — `post_link_entries/1` calls `PostLinks.list_incoming_links/1` and `Posts.get_post/1` per link during render.
  - `panel_renderer.ex:229-240` — `git_log_entries/1` calls `Git.file_history/2` and `Posts.get_post/1` during render.
  - `tab_helpers.ex:120-135` — `derived_tab_meta/1` queries posts, media, scripts, templates, chat conversations, and import definitions from within the render-prep path.
- **Fix:** Move all data fetching into event handlers (`handle_event`) or the decomposed `reload_shell` updaters from CSM-007. Pre-compute link entries and git log entries when a tab becomes active and store them in assigns. Render should be a pure function of assigns.
- **Test:** Render a panel 10 times; assert no DB queries fire on re-renders.

---

### CSM-009 — Thumbnail Generation: Missing Error Handling
- **File:** `lib/bds/media/thumbnails.ex:107-165`
- **What:**
  - `Image.thumbnail!` (Z. 149,154) and `Image.write!` (Z. 159,164) are bang variants that crash on failure.
  - `File.mkdir_p/1` (Z. 133) result is discarded — if directory creation fails, the write will crash with a confusing error.
  - `Image.embed!` (Z. 150) and `Image.flatten!` (Z. 158) are also bang variants.
- **Note on scheduler blocking:** The `Image` library uses libvips NIFs which run image processing in a C thread pool, not on the BEAM scheduler. The original concern about scheduler blocking is **not substantiated** for this library. The real issues are the bang variants and unchecked `File.mkdir_p`.
- **Fix:**
  - Replace `File.mkdir_p/1` with `case File.mkdir_p(dir) do :ok -> ...; {:error, reason} -> {:error, reason}`.
  - Replace bang `Image.thumbnail!` with `Image.thumbnail` and handle `{:error, _}`.
  - Replace bang `Image.write!` with `Image.write` and handle `{:error, _}`.
  - Wrap the whole `write_all_thumbnails` in a try/return-error-tuple pattern.
- **Test:** Feed a corrupt image; assert `ensure_thumbnails` returns `{:error, _}` instead of crashing.

---

### CSM-010 — `rescue` for Control Flow in Data Layer
- **File:** `lib/bds/desktop/shell_data.ex:64-74, 81-103, 152-182`
- **What:** `rescue Exqlite.Error`, `rescue DBConnection.OwnershipError` to return empty defaults in `project_snapshot/0`, `dashboard/1`, `sidebar_view/3`, and `git_badge_count/2`.
- **Why it's bad:** Exceptions are for exceptional conditions. The rescue here handles the boot-phase case where the DB table doesn't exist yet — this is an expected state during startup.
- **Nuance:** The code does check `Exception.message(error)` for "no such table" and re-raises everything else, which limits the damage. But it's still control-flow-via-exception.
- **Fix:** Add an explicit `DB.ready?/0` check (or `Ecto.Adapters.SQL.query!/2` with a lightweight probe) before calling the data functions. Return `{:ok, result}` / `{:error, :not_ready}` tuples from the lowest-level callers and handle them upstream. Only `rescue` for truly unexpected DB errors.
- **Test:** Call `project_snapshot/0` with no DB connection; assert it returns `{:error, :not_ready}` instead of a default map.

---

## Medium Severity

### CSM-011 — No URL State / Deep Linking
- **File:** `lib/bds/desktop/shell_live.ex`, `lib/bds/desktop/router.ex`
- **What:** Tabs, filters, and selected items are never reflected in the URL. No `handle_params/3` or `push_patch/2` is used anywhere in the codebase.
- **Why it's bad:** Users cannot bookmark or use the back button. Harder to debug.
- **Mitigating factor:** This is a desktop app (wx container), not a web app. URL-based navigation is less critical but still valuable for debuggability and for when the app is accessed via a browser during development.
- **Fix:** Add `handle_params/3` for at least `?tab=` and `?view=` params. Use `push_patch` on state changes.
- **Test:** Click a tab; assert the URL updates to `/?tab=posts`; refresh; assert the same tab is active.

---

### CSM-012 — Desktop File Dialog Blocks Event Handler
- **File:** `lib/bds/desktop/shell_live/sidebar_create.ex:44-69`
- **What:** `FilePicker.choose_file/1` is called directly inside `handle_event`.
- **Why it's bad:** Can freeze the socket process while the native dialog is open.
- **Mitigating factor:** In a desktop app, the user flow naturally waits for the dialog result. The risk is low in practice.
- **Fix:** Spawn a short-lived `Task` or use Desktop library's non-blocking async APIs.
- **Test:** Trigger a file picker; send another event immediately; assert the second event is handled within 100ms.

---

### CSM-013 — Bang Functions in Rendering Pipelines
- **Files:** `lib/bds/rendering/post_rendering.ex:151`, `lib/bds/rendering/filters.ex:125,127`, `lib/bds/rendering/template_selection.ex:92,102`
- **What:** `Jason.encode!`, `Liquex.parse!`, `Liquex.render!` crash on bad data instead of returning errors.
- **Fix:** Use non-bang variants, wrap in `case`, and propagate `{:error, reason}` to the caller.
- **Test:** Feed a template with a syntax error; assert the renderer returns `{:error, _}` rather than raising.

---

### CSM-014 — O(n²) Loops from `length/1` Inside Iteration
- **Files:**
  - `lib/bds/publishing.ex:127` — `length(targets)` inside `Enum.reduce_while` (typically 3 targets, negligible impact)
  - `lib/bds/rendering/list_archive.ex:299` — `index < length(grouped_blocks) - 1` inside `Enum.map`
  - `lib/bds/generation/outputs.ex:216,230,232` — repeated `length(paginated_posts)` and `length(posts)` inside comprehensions
  - `lib/bds/ui/sidebar.ex:556-565` — `acc.draft ++ [post]` in `Enum.reduce` (also covered by CSM-024)
- **Note:** In `publishing.ex` the O(n²) is negligible (3 targets). The real impact is in `outputs.ex` and `list_archive.ex` with large post sets.
- **Fix:** Bind `total = length(list)` before the loop. For `acc ++ [item]`, use reverse-accumulate + `Enum.reverse`.
- **Test:** Run the function with a list of 1,000 items; assert it completes in linear time.

---

### CSM-015 — Missing DB Indexes on Foreign Keys
- **Files:** `priv/repo/migrations/20260423120000_create_persistence_contract.exs`
- **What:** The initial migration uses `references(...)` which creates FK constraints but does NOT create dedicated indexes for most FKs. Missing indexes on:
  - `media.project_id` (queried in every sidebar/dashboard load)
  - `post_media.post_id`, `post_media.media_id`
  - `chat_messages.conversation_id`
  - `embedding_keys.post_id`, `embedding_keys.project_id`
  - `dismissed_duplicate_pairs.project_id`
  - `import_definitions.project_id`
  - `db_notifications.entity_type`, `db_notifications.entity_id`
  - `posts.status`, `posts.published_at`, `posts.language` — frequently filtered columns
- **Note:** SQLite is more forgiving than PostgreSQL for missing FK indexes, but with growing data the query plans will degrade.
- **Fix:** Add a new migration with `create index` for every foreign key and frequently filtered column.
- **Test:** Verify with `sqlite3` `EXPLAIN QUERY PLAN` that key lookups use indexes.

---

### CSM-016 — String Concatenation for Paths
- **Files:**
  - `lib/bds/rendering/metadata.ex:43` — `"/#{slug}/"`
  - `lib/bds/rendering/metadata.ex:112` — `prefix <> "/"`
  - `lib/bds/publishing.ex:284` — `String.trim_trailing(path, "/") <> "/"`
  - `lib/bds/rendering/file_system.ex:29` — `normalized_path <> ".liquid"`
  - `lib/bds/rendering/links_and_languages.ex` — path construction with `<>`
- **Fix:** Use `Path.join/1-2` and `Path.extname` / `Path.rootname`. For `"/#{slug}/"`, use `Path.join(["/", slug])` or `"/" <> slug <> "/"` → `URI.encode(slug)` is already used elsewhere.
- **Test:** Test paths with trailing slashes, empty segments, and special characters.

---

### CSM-017 — `send(self(), ...)` Component Chatter
- **Files:** 25+ call sites across editor components:
  - `lib/bds/desktop/shell_live/script_editor.ex` (3 sends)
  - `lib/bds/desktop/shell_live/post_editor.ex` (2 sends)
  - `lib/bds/desktop/shell_live/template_editor.ex` (3 sends)
  - `lib/bds/desktop/shell_live/media_editor.ex` (2 sends)
  - `lib/bds/desktop/shell_live/chat_editor.ex` (1 send)
  - `lib/bds/desktop/shell_live/menu_editor.ex` (1 send)
  - `lib/bds/desktop/shell_live/settings_editor.ex` (2 sends)
  - `lib/bds/desktop/shell_live/misc_editor.ex` (4 sends)
  - `lib/bds/desktop/shell_live/tags_editor.ex` (2 sends)
  - `lib/bds/desktop/shell_live/import_editor.ex` (1 send)
  - `lib/bds/desktop/shell_live/overlay_manager.ex` (3 sends)
  - `lib/bds/desktop/main_window.ex` (1 send)
- **What:** Components send messages to the parent via `send(self(), ...)`, forcing a broad `handle_info` in `ShellLive`. Each message type must be handled in the parent, creating tight coupling.
- **Fix:** Prefer `Phoenix.LiveView.send_update/2` for targeted component updates, or delegate through a single dispatch module that translates actions into specific state changes.
- **Test:** Refactor one component; assert it no longer uses `send(self(), ...)`.

---

## Low Severity / Code Quality

### CSM-018 — `@moduledoc false` Epidemic
- **Files:** `lib/bds/i18n.ex`, `lib/bds/map_utils.ex`, `lib/bds/bounded_atoms.ex`, `lib/bds/document_fields.ex`, `lib/bds/import_definitions.ex`, `lib/bds/publishing.ex`, `lib/bds/settings.ex`, `lib/bds/templates.ex`, `lib/bds/ai.ex`, `lib/bds/mcp.ex`, `lib/bds/scripting/capabilities.ex`, `lib/bds/scripting/api_docs.ex`
- **Fix:** Write `@moduledoc` descriptions for all public modules. Keep internal helpers documented or mark them `@moduledoc false` only if truly private.

---

### CSM-019 — Missing `@spec` on Public Functions
- **Files:** Widespread across rendering, generation, publishing, UI, and scripting modules.
- **Fix:** Add `@spec` to every public function. This is a Dialyzer prerequisite (the project already runs Dialyzer; the report notes it should be clean).

---

### CSM-020 — Deeply Nested `case` Instead of `with`
- **Files:** `lib/bds/import_definitions.ex:54-66`, `lib/bds/publishing.ex:47-58`, `lib/bds/templates.ex:86-163`
- **Fix:** Flatten with `with`:
  ```elixir
  with {:ok, record} <- Repo.get(Model, id),
       {:ok, updated} <- Repo.update(changeset) do
    {:ok, updated}
  else
    nil -> {:error, :not_found}
    {:error, changeset} -> {:error, changeset}
  end
  ```

---

### CSM-021 — `cond` Where Pattern Matching Suffices
- **Files:** `lib/bds/ai.ex:62-70`, `lib/bds/scripting/api_docs.ex:1345-1398`, `lib/bds/scripting/api_docs.ex:1433-1447`
- **Fix:** Replace `cond do x == nil -> ...; true -> ... end` with multiple function-head clauses.

---

### CSM-022 — Silent Error Swallowing
- **File:** `lib/bds/scripting.ex:64-66`
- **What:** `execute_macro/4` returns `{:ok, ""}` on `{:error, _reason}` with no logging. The caller cannot distinguish success from failure.
- **Fix:** Return the actual error tuple or at least log the failure with `Logger.error/1`.

---

### CSM-023 — SRP Violations
- **Files:**
  - `lib/bds/templates.ex:86-163` — `update_template/2` does slug changes, content changes, status transitions, file paths, transactions, cascades, and filesystem sync.
  - `lib/bds/scripting/capabilities.ex:22-248` — `for_project/2` returns a 200+ line map literal.
- **Fix:** Decompose into smaller private pipelines or domain-specific builder functions.

---

### CSM-024 — `Enum.reduce` with `acc.draft ++ [post]` (O(n²))
- **File:** `lib/bds/ui/sidebar.ex:556-565`
- **Fix:** Use `Enum.group_by/3` or reverse-accumulate and `Enum.reverse`.

---

### CSM-025 — Hardcoded Language Prefixes
- **File:** `lib/bds/generation/pagefind.ex:48-54`
- **What:** `["de/", "fr/", "it/", "es/"]` hardcoded instead of derived from project settings.
- **Fix:** Derive from project settings (`mainLanguage` and supported languages).

---

### CSM-026 — TOCTOU Race Condition in Template File System
- **File:** `lib/bds/rendering/file_system.ex:28-37`
- **What:** `Enum.find(&File.regular?/1)` checks existence, then the file is read later (in the `Liquex.FileSystem` impl, Z. 43-49). Between check and read the file can vanish.
- **Fix:** Just try to read and handle `{:error, :enoent}`. Remove the `Enum.find` existence check and attempt reads directly.

---

### CSM-027 — `if result == :ok` Instead of Pattern Matching
- **File:** `lib/bds/templates.ex:445`
- **Fix:** Use `case result do :ok -> ...; _ -> ... end`.

---

### CSM-028 — Broad `rescue` Swallowing Template Errors
- **File:** `lib/bds/rendering/filters.ex:130-132`
- **What:** `rescue _error -> ""` swallows all macro template failures silently.
- **Fix:** Rescue only specific exceptions, or return `{:error, exception}` and let the caller decide.

---

### CSM-029 — `length/1` in Guards or Comparisons
- **Files:** `lib/bds/generation/outputs.ex`, `lib/bds/ui/sidebar.ex`
- **What:** `length(list)` is O(n). Using it inside a loop makes the whole loop O(n²).
- **Fix:** Bind the length before the loop.

---

### CSM-030 — Unchecked `File.mkdir_p` / `File.mkdir_p!`
- **Files:** `lib/bds/media/thumbnails.ex:133`, `lib/bds/media/sidecars.ex:24,56`, `lib/bds/release_packaging.ex:80,85`
- **What:** Result of `File.mkdir_p/1` is discarded. `File.mkdir_p!/1` in `release_packaging` can crash on permission errors.
- **Fix:** Pattern-match `File.mkdir_p/1` or use `with`; replace bang variants with non-bang and handle errors.

---

### CSM-031 — `try/rescue` Instead of `with` and Error Tuples
- **Files:** `lib/bds/rendering/filters.ex`, `lib/bds/rendering/template_selection.ex`, `lib/bds/desktop/shell_data.ex`
- **Fix:** Replace `try/rescue` around expected failures with non-bang functions and `with` chains.

---

### CSM-032 — `Map.get` with Default Instead of Pattern Matching
- **Files:** Widespread
- **What:** `Map.get(map, key, default)` when the key is expected to exist.
- **Fix:** Use pattern matching (`%{key: value} = map`) or `Map.fetch!/2` if the key is required.

---

### CSM-033 — `Enum.each` with Side Effects That Should Be Batch Inserts
- **Files:** `lib/bds/search.ex:174-177`, `lib/bds/embeddings.ex`
- **What:** `Enum.each` used for inserting records. The side-effect pattern is fine, but `Enum.map` + `Repo.insert_all` would be much faster for bulk inserts.
- **Fix:** Use `Repo.insert_all` for batch inserts instead of `Enum.each` + `Repo.insert`.

---

### CSM-034 — `File.read!` / `File.write!` Without Error Handling
- **Files:** `lib/bds/preview_assets.ex:32`, `lib/bds/release_packaging.ex:105`, `lib/bds/templates.ex:488-489`
- **Fix:** Use `File.read/1`, `File.write/2`, and handle `{:error, reason}`.

---

### CSM-035 — Process Dictionary (`Process.get/put`) Usage
- **File:** `lib/bds/desktop/ui_locale.ex:32,49,65`
- **What:** `UILocale.put/1` sets process dictionary (`Process.put(@key, locale)`) for UI locale. Used in `ShellLive.render` (Z. 550) and `MenuBar`.
- **Fix:** This is isolated to the LiveView/MenuBar process so it's low-risk, but document the invariant explicitly: the process dict key `:bds_ui_locale` is set before each render call.

---

### CSM-036 — Missing `@impl true` on GenServer Callbacks
- **File:** `lib/bds/publishing.ex:46,61,71,75`
- **What:** Only `init/1` (Z. 36) and the first `handle_call` (Z. 41) have `@impl true`. The remaining `handle_call` clauses at Z. 46, 61, 71, 75 lack it.
- **Fix:** Add `@impl true` before every `handle_call`, `handle_cast`, `handle_info`, and `terminate`.

---

## Checklist for Agents Picking Up This File

- [x] All critical items (CSM-001 to CSM-005) have been addressed or explicitly deferred with justification.
  - CSM-001: Fixed. All `String.to_atom` on dynamic data replaced with `MapUtils.safe_atomize_key/keys` or `String.to_existing_atom`.
  - CSM-002: Fixed. Search now pushes all filtering and pagination into SQL via Ecto queries and CTEs.
- [ ] All high-severity items (CSM-006 to CSM-010) have been addressed.
- [x] CSM-001 fix covers ALL 6 affected files, not just `import_definitions.ex`.
- [x] CSM-003 fix covers ALL `Repo.delete!` call sites (posts, tags, scripts, media, projects, templates, translations).
- [ ] CSM-007 decomposition is the prerequisite for fixing CSM-008 (render-path queries).
- [x] Tests were written **before** implementation changes (Red → Green → Refactor).
- [x] Full test suite passes: `mix test`.
- [x] Dialyzer passes cleanly: `mix dialyzer` (zero warnings).
- [x] Build succeeds: `mix compile`.
- [x] No external JS/CSS referenced in preview/generated HTML (per AGENTS.md).
- [x] All UI strings use gettext / i18n, no hardcoded text.
- [x] API docs (`API.md`) updated if any API changes were made.
- [x] Metadata diff tool and rebuild-from-database updated if metadata changed.
- [x] Specs in `specs/` folder updated and validated if behavior changed.
- [x] Unused code (including tests for removed features) has been deleted.
- [x] This `CODESMELL.md` updated: fixed items removed, new ones added.