diff --git a/lib/philomena/comments.ex b/lib/philomena/comments.ex
index 2d2360fe..f7db9dfc 100644
--- a/lib/philomena/comments.ex
+++ b/lib/philomena/comments.ex
@@ -119,6 +119,20 @@ defmodule Philomena.Comments do
     Repo.delete(comment)
   end
 
+  @doc """
+  Hides a comment and handles associated reports.
+
+  ## Parameters
+  - comment: The comment to hide
+  - attrs: Attributes for the hide operation
+  - user: The user performing the hide action
+
+  ## Examples
+
+      iex> hide_comment(comment, %{staff_note: "Rule violation"}, user)
+      {:ok, %Comment{}}
+
+  """
   def hide_comment(%Comment{} = comment, attrs, user) do
     report_query = Reports.close_report_query({"Comment", comment.id}, user)
     comment = Comment.hide_changeset(comment, attrs, user)
@@ -139,6 +153,15 @@ defmodule Philomena.Comments do
     end
   end
 
+  @doc """
+  Unhides a previously hidden comment.
+
+  ## Examples
+
+      iex> unhide_comment(comment)
+      {:ok, %Comment{}}
+
+  """
   def unhide_comment(%Comment{} = comment) do
     comment
     |> Comment.unhide_changeset()
@@ -154,12 +177,35 @@ defmodule Philomena.Comments do
     end
   end
 
+  @doc """
+  Marks a comment as destroyed and removes its text (hard deletion).
+
+  ## Examples
+
+      iex> destroy_comment(comment)
+      {:ok, %Comment{}}
+
+  """
   def destroy_comment(%Comment{} = comment) do
     comment
     |> Comment.destroy_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Approves a comment, closes associated reports, and increments the user comments
+  posted count.
+
+  ## Parameters
+  - comment: The comment to approve
+  - user: The user performing the approval
+
+  ## Examples
+
+      iex> approve_comment(comment, user)
+      {:ok, %Comment{}}
+
+  """
   def approve_comment(%Comment{} = comment, user) do
     report_query = Reports.close_report_query({"Comment", comment.id}, user)
     comment = Comment.approve_changeset(comment)
@@ -181,6 +227,23 @@ defmodule Philomena.Comments do
     end
   end
 
+  @doc """
+  Creates a system report for non-approved comments containing external images.
+  Returns false for already approved comments.
+
+  ## Returns
+  - `false`: If the comment is already approved
+  - `{:ok, %Report{}}`: If a system report was created
+
+  ## Examples
+
+      iex> report_non_approved(approved_comment)
+      false
+
+      iex> report_non_approved(unapproved_comment)
+      {:ok, %Report{}}
+
+  """
   def report_non_approved(%Comment{approved: true}), do: false
 
   def report_non_approved(comment) do
@@ -191,6 +254,20 @@ defmodule Philomena.Comments do
     )
   end
 
+  @doc """
+  Migrates comments from one image to another when handling duplicate images.
+  Returns the duplicate image parameter unchanged, for use in a pipeline.
+
+  ## Parameters
+  - image: The source image whose comments will be moved
+  - duplicate_of_image: The target image that will receive the comments
+
+  ## Examples
+
+      iex> migrate_comments(source_image, target_image)
+      %Image{}
+
+  """
   def migrate_comments(image, duplicate_of_image) do
     {count, nil} =
       Comment
@@ -217,24 +294,62 @@ defmodule Philomena.Comments do
     Comment.changeset(comment, %{})
   end
 
+  @doc """
+  Updates comment search indices when a user's name changes.
+
+  ## Examples
+
+      iex> user_name_reindex("old_username", "new_username")
+      :ok
+
+  """
   def user_name_reindex(old_name, new_name) do
     data = CommentIndex.user_name_update_by_query(old_name, new_name)
 
     Search.update_by_query(Comment, data.query, data.set_replacements, data.replacements)
   end
 
+  @doc """
+  Queues a single comment for search index updates.
+  Returns the comment struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_comment(comment)
+      %Comment{}
+
+  """
   def reindex_comment(%Comment{} = comment) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Comments", "id", [comment.id]])
 
     comment
   end
 
+  @doc """
+  Queues all comments associated with an image for search index updates.
+  Returns the image struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_comments(image)
+      %Image{}
+
+  """
   def reindex_comments(image) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Comments", "image_id", [image.id]])
 
     image
   end
 
+  @doc """
+  Provides preload queries for comment indexing operations.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [user: user_query, image: image_query]
+
+  """
   def indexing_preloads do
     user_query = select(User, [u], map(u, [:id, :name]))
     tag_query = select(Tag, [t], map(t, [:id]))
@@ -250,6 +365,22 @@ defmodule Philomena.Comments do
     ]
   end
 
+  @doc """
+  Performs a search reindex operation on comments matching the given criteria.
+
+  ## Parameters
+  - column: The database column to filter on (e.g., :id, :image_id)
+  - condition: A list of values to match against the column
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      :ok
+
+      iex> perform_reindex(:image_id, [123])
+      :ok
+
+  """
   def perform_reindex(column, condition) do
     Comment
     |> preload(^indexing_preloads())
diff --git a/lib/philomena/dnp_entries.ex b/lib/philomena/dnp_entries.ex
index 03946710..96b9bd5a 100644
--- a/lib/philomena/dnp_entries.ex
+++ b/lib/philomena/dnp_entries.ex
@@ -77,6 +77,18 @@ defmodule Philomena.DnpEntries do
     |> Repo.update()
   end
 
+  @doc """
+  Transitions a DNP entry to a new state.
+
+  ## Examples
+
+      iex> transition_dnp_entry(dnp_entry, user, "acknowledged")
+      {:ok, %DnpEntry{}}
+
+      iex> transition_dnp_entry(dnp_entry, user, "invalid_state")
+      {:error, %Ecto.Changeset{}}
+
+  """
   def transition_dnp_entry(%DnpEntry{} = dnp_entry, user, new_state) do
     dnp_entry
     |> DnpEntry.transition_changeset(user, new_state)
@@ -112,6 +124,19 @@ defmodule Philomena.DnpEntries do
     DnpEntry.changeset(dnp_entry, %{})
   end
 
+  @doc """
+  Returns the count of active DNP entries in requested, claimed,
+  or acknowledged state, if the user has permission to view them.
+
+  ## Examples
+
+      iex> count_dnp_entries(admin)
+      42
+
+      iex> count_dnp_entries(user)
+      nil
+
+  """
   def count_dnp_entries(user) do
     if Canada.Can.can?(user, :index, DnpEntry) do
       DnpEntry
diff --git a/lib/philomena/duplicate_reports.ex b/lib/philomena/duplicate_reports.ex
index a9cad67b..a920e87a 100644
--- a/lib/philomena/duplicate_reports.ex
+++ b/lib/philomena/duplicate_reports.ex
@@ -16,6 +16,18 @@ defmodule Philomena.DuplicateReports do
   alias Philomena.Images.Image
   alias Philomena.Images
 
+  @doc """
+  Generates automated duplicate reports for an image based on perceptual matching.
+
+  Takes a source image and generates duplicate reports for similar images based on
+  intensity and aspect ratio comparison.
+
+  ## Examples
+
+      iex> generate_reports(source_image)
+      [{:ok, %DuplicateReport{}}, ...]
+
+  """
   def generate_reports(source) do
     source = Repo.preload(source, :intensity)
 
@@ -30,6 +42,23 @@ defmodule Philomena.DuplicateReports do
     end)
   end
 
+  @doc """
+  Query for potential duplicate images based on intensity values and aspect ratio.
+
+  Takes a tuple of {intensities, aspect_ratio} and optional options to control the search:
+  - `:aspect_dist` - Maximum aspect ratio difference (default: 0.05)
+  - `:limit` - Maximum number of results (default: 10)
+  - `:dist` - Maximum intensity difference per channel (default: 0.25)
+
+  ## Examples
+
+      iex> find_duplicates({%{nw: 0.5, ne: 0.5, sw: 0.5, se: 0.5}, 1.0})
+      #Ecto.Query<...>
+
+      iex> find_duplicates({intensities, ratio}, dist: 0.3, limit: 20)
+      #Ecto.Query<...>
+
+  """
   def find_duplicates({intensities, aspect_ratio}, opts \\ []) do
     aspect_dist = Keyword.get(opts, :aspect_dist, 0.05)
     limit = Keyword.get(opts, :limit, 10)
@@ -150,6 +179,21 @@ defmodule Philomena.DuplicateReports do
     |> Repo.insert()
   end
 
+  @doc """
+  Accepts a duplicate report and merges the duplicate image into the target image.
+
+  Takes an optional Ecto.Multi, the duplicate report to accept, and the user accepting the report.
+  Handles rejecting any other duplicate reports between the same images and merges the images.
+
+  ## Examples
+
+      iex> accept_duplicate_report(nil, duplicate_report, user)
+      {:ok, %{duplicate_report: %DuplicateReport{}, ...}}
+
+      iex> accept_duplicate_report(existing_multi, duplicate_report, user)
+      %Ecto.Multi{}
+
+  """
   def accept_duplicate_report(multi \\ nil, %DuplicateReport{} = duplicate_report, user) do
     duplicate_report = Repo.preload(duplicate_report, [:image, :duplicate_of_image])
 
@@ -175,6 +219,18 @@ defmodule Philomena.DuplicateReports do
     |> Images.merge_image(duplicate_report.image, duplicate_report.duplicate_of_image, user)
   end
 
+  @doc """
+  Accepts a duplicate report in reverse, making the target image the duplicate instead.
+
+  Creates a new duplicate report with reversed image relationship if one doesn't exist,
+  rejects the original report, and accepts the reversed report.
+
+  ## Examples
+
+      iex> accept_reverse_duplicate_report(duplicate_report, user)
+      {:ok, %{duplicate_report: %DuplicateReport{}, ...}}
+
+  """
   def accept_reverse_duplicate_report(%DuplicateReport{} = duplicate_report, user) do
     new_report =
       DuplicateReport
@@ -204,18 +260,47 @@ defmodule Philomena.DuplicateReports do
     |> accept_duplicate_report(new_report, user)
   end
 
+  @doc """
+  Claims a duplicate report for review by a user.
+
+  ## Examples
+
+      iex> claim_duplicate_report(duplicate_report, user)
+      {:ok, %DuplicateReport{}}
+
+  """
   def claim_duplicate_report(%DuplicateReport{} = duplicate_report, user) do
     duplicate_report
     |> DuplicateReport.claim_changeset(user)
     |> Repo.update()
   end
 
+  @doc """
+  Removes a user's claim on a duplicate report.
+
+  ## Examples
+
+      iex> unclaim_duplicate_report(duplicate_report)
+      {:ok, %DuplicateReport{}}
+
+  """
   def unclaim_duplicate_report(%DuplicateReport{} = duplicate_report) do
     duplicate_report
     |> DuplicateReport.unclaim_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Rejects a duplicate report.
+
+  Updates the duplicate report's state to rejected and records the user who rejected it.
+
+  ## Examples
+
+      iex> reject_duplicate_report(duplicate_report, user)
+      {:ok, %DuplicateReport{}}
+
+  """
   def reject_duplicate_report(%DuplicateReport{} = duplicate_report, user) do
     duplicate_report
     |> DuplicateReport.reject_changeset(user)
@@ -251,6 +336,19 @@ defmodule Philomena.DuplicateReports do
     DuplicateReport.changeset(duplicate_report, %{})
   end
 
+  @doc """
+  Counts the number of duplicate reports in "open" state,
+  if the user has permission to view them.
+
+  ## Examples
+
+      iex> count_duplicate_reports(admin)
+      42
+
+      iex> count_duplicate_reports(user)
+      nil
+
+  """
   def count_duplicate_reports(user) do
     if Canada.Can.can?(user, :index, DuplicateReport) do
       DuplicateReport
diff --git a/lib/philomena/filters.ex b/lib/philomena/filters.ex
index 6ff7daa4..67147b0c 100644
--- a/lib/philomena/filters.ex
+++ b/lib/philomena/filters.ex
@@ -93,6 +93,17 @@ defmodule Philomena.Filters do
     |> reindex_after_update()
   end
 
+  @doc """
+  Makes a filter public.
+
+  Updates the filter to be publicly accessible by other users.
+
+  ## Examples
+
+      iex> make_filter_public(filter)
+      {:ok, %Filter{}}
+
+  """
   def make_filter_public(%Filter{} = filter) do
     filter
     |> Filter.public_changeset()
@@ -140,6 +151,21 @@ defmodule Philomena.Filters do
     Filter.changeset(filter, %{})
   end
 
+  @doc """
+  Returns a grouped list of recent and user filters.
+
+  Takes a user and returns a list of their recently used filters and personal filters,
+  grouped into "Recent Filters" and "Your Filters" categories.
+
+  ## Examples
+
+      iex> recent_and_user_filters(user)
+      [
+        {"Recent Filters", [[key: "Filter 1", value: 1], ...]},
+        {"Your Filters", [[key: "Filter 2", value: 2], ...]}
+      ]
+
+  """
   def recent_and_user_filters(user) do
     recent_filter_ids =
       [user.current_filter_id | user.recent_filter_ids]
@@ -174,6 +200,17 @@ defmodule Philomena.Filters do
     |> Enum.reverse()
   end
 
+  @doc """
+  Adds a tag to a filter's hidden tags list.
+
+  Updates the filter to hide content with the specified tag.
+
+  ## Examples
+
+      iex> hide_tag(filter, tag)
+      {:ok, %Filter{}}
+
+  """
   def hide_tag(filter, tag) do
     hidden_tag_ids = Enum.uniq([tag.id | filter.hidden_tag_ids])
 
@@ -183,6 +220,15 @@ defmodule Philomena.Filters do
     |> reindex_after_update()
   end
 
+  @doc """
+  Removes a tag from a filter's hidden tags list.
+
+  ## Examples
+
+      iex> unhide_tag(filter, tag)
+      {:ok, %Filter{}}
+
+  """
   def unhide_tag(filter, tag) do
     hidden_tag_ids = filter.hidden_tag_ids -- [tag.id]
 
@@ -192,6 +238,15 @@ defmodule Philomena.Filters do
     |> reindex_after_update()
   end
 
+  @doc """
+  Adds a tag to a filter's spoilered tags list.
+
+  ## Examples
+
+      iex> spoiler_tag(filter, tag)
+      {:ok, %Filter{}}
+
+  """
   def spoiler_tag(filter, tag) do
     spoilered_tag_ids = Enum.uniq([tag.id | filter.spoilered_tag_ids])
 
@@ -201,6 +256,15 @@ defmodule Philomena.Filters do
     |> reindex_after_update()
   end
 
+  @doc """
+  Removes a tag from a filter's spoilered tags list.
+
+  ## Examples
+
+      iex> unspoiler_tag(filter, tag)
+      {:ok, %Filter{}}
+
+  """
   def unspoiler_tag(filter, tag) do
     spoilered_tag_ids = filter.spoilered_tag_ids -- [tag.id]
 
@@ -210,38 +274,92 @@ defmodule Philomena.Filters do
     |> reindex_after_update()
   end
 
-  defp reindex_after_update({:ok, filter}) do
-    reindex_filter(filter)
+  defp reindex_after_update(result) do
+    case result do
+      {:ok, filter} ->
+        reindex_filter(filter)
 
-    {:ok, filter}
+        {:ok, filter}
+
+      error ->
+        error
+    end
   end
 
-  defp reindex_after_update(error) do
-    error
-  end
+  @doc """
+  Updates filter indexes when a user's name changes.
 
+  Updates search indexes to reflect a user's new name.
+
+  ## Examples
+
+      iex> user_name_reindex("old_name", "new_name")
+      :ok
+
+  """
   def user_name_reindex(old_name, new_name) do
     data = FilterIndex.user_name_update_by_query(old_name, new_name)
 
     Search.update_by_query(Filter, data.query, data.set_replacements, data.replacements)
   end
 
+  @doc """
+  Queues a single filter for search index updates.
+  Returns the filter struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_filter(filter)
+      %Filter{}
+
+  """
   def reindex_filter(%Filter{} = filter) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Filters", "id", [filter.id]])
 
     filter
   end
 
+  @doc """
+  Removes a filter from the search index.
+
+  ## Examples
+
+      iex> unindex_filter(filter)
+      %Filter{}
+
+  """
   def unindex_filter(%Filter{} = filter) do
     Search.delete_document(filter.id, Filter)
 
     filter
   end
 
+  @doc """
+  Returns a list of associations to preload when indexing filters.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [:user]
+
+  """
   def indexing_preloads do
     [:user]
   end
 
+  @doc """
+  Performs a search reindex operation on filters matching the given criteria.
+
+  ## Parameters
+  - column: The database column to filter on (e.g., :id)
+  - condition: A list of values to match against the column
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      {:ok, [%Filter{}, ...]}
+
+  """
   def perform_reindex(column, condition) do
     Filter
     |> preload(^indexing_preloads())
diff --git a/lib/philomena/galleries.ex b/lib/philomena/galleries.ex
index d36198b7..35bc156a 100644
--- a/lib/philomena/galleries.ex
+++ b/lib/philomena/galleries.ex
@@ -121,6 +121,15 @@ defmodule Philomena.Galleries do
     Gallery.changeset(gallery, %{})
   end
 
+  @doc """
+  Updates gallery search indices when a user's name changes.
+
+  ## Examples
+
+      iex> user_name_reindex("old_username", "new_username")
+      :ok
+
+  """
   def user_name_reindex(old_name, new_name) do
     data = GalleryIndex.user_name_update_by_query(old_name, new_name)
 
@@ -137,22 +146,65 @@ defmodule Philomena.Galleries do
     error
   end
 
+  @doc """
+  Queues a gallery for reindexing.
+
+  Adds the gallery to the indexing queue to update its search index.
+
+  ## Examples
+
+      iex> reindex_gallery(gallery)
+      %Gallery{}
+
+  """
   def reindex_gallery(%Gallery{} = gallery) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Galleries", "id", [gallery.id]])
 
     gallery
   end
 
+  @doc """
+  Removes a gallery from the search index.
+
+  Deletes the gallery's document from the search index.
+
+  ## Examples
+
+      iex> unindex_gallery(gallery)
+      %Gallery{}
+
+  """
   def unindex_gallery(%Gallery{} = gallery) do
     Search.delete_document(gallery.id, Gallery)
 
     gallery
   end
 
+  @doc """
+  Returns a list of associations to preload when indexing galleries.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [:subscribers, :creator, :interactions]
+
+  """
   def indexing_preloads do
     [:subscribers, :creator, :interactions]
   end
 
+  @doc """
+  Reindexes galleries based on a column condition.
+
+  Updates the search index for all galleries matching the given column condition.
+  Used for batch reindexing of galleries.
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      {:ok, [%Gallery{}, ...]}
+
+  """
   def perform_reindex(column, condition) do
     Gallery
     |> preload(^indexing_preloads())
@@ -160,6 +212,24 @@ defmodule Philomena.Galleries do
     |> Search.reindex(Gallery)
   end
 
+  @doc """
+  Adds the specified image to the gallery, updates image count, triggers
+  notifications, and performs necessary reindexing.
+
+  The image is added at the last position.
+
+  ## Examples
+
+      iex> add_image_to_gallery(gallery, image)
+      {:ok,
+       %{
+         gallery: %Gallery{},
+         interaction: %Interaction{},
+         image_count: 1,
+         notification: %Notification{}
+       }}
+
+  """
   def add_image_to_gallery(gallery, image) do
     Multi.new()
     |> Multi.run(:gallery, fn repo, %{} ->
@@ -202,6 +272,21 @@ defmodule Philomena.Galleries do
     end
   end
 
+  @doc """
+  Removes the specified image from the gallery, updates image count,
+  and performs necessary reindexing.
+
+  ## Examples
+
+      iex> remove_image_from_gallery(gallery, image)
+      {:ok,
+       %{
+         gallery: %Gallery{},
+         interaction: 1,
+         image_count: 0
+       }}
+
+  """
   def remove_image_from_gallery(gallery, image) do
     Multi.new()
     |> Multi.run(:gallery, fn repo, %{} ->
@@ -254,10 +339,35 @@ defmodule Philomena.Galleries do
     |> Repo.aggregate(:max, :position)
   end
 
+  @doc """
+  Queues a gallery reorder operation.
+  Returns the gallery struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reorder_gallery(gallery, [1, 2, 3])
+      %Gallery{}
+
+  """
   def reorder_gallery(gallery, image_ids) do
     Exq.enqueue(Exq, "indexing", GalleryReorderWorker, [gallery.id, image_ids])
+
+    gallery
   end
 
+  @doc """
+  Performs the actual reordering of images in a gallery.
+
+  Reorders the gallery's images according to the provided image IDs list, updating
+  positions while maintaining relative order for unspecified images. Handles position
+  updates efficiently and reindexes only the affected images.
+
+  ## Examples
+
+      iex> perform_reorder(gallery_id, [3, 1, 2])
+      :ok
+
+  """
   def perform_reorder(gallery_id, image_ids) do
     gallery = get_gallery!(gallery_id)
 
@@ -320,6 +430,8 @@ defmodule Philomena.Galleries do
 
     # Now update all the associated images
     Images.reindex_images(Map.keys(requested))
+
+    :ok
   end
 
   defp position_order(%{order_position_asc: true}), do: [asc: :position]
diff --git a/lib/philomena/images.ex b/lib/philomena/images.ex
index af0ef79f..3d69ab99 100644
--- a/lib/philomena/images.ex
+++ b/lib/philomena/images.ex
@@ -156,6 +156,16 @@ defmodule Philomena.Images do
     Logger.error("Aborting upload of #{image.id} after #{retry_count} retries")
   end
 
+  @doc """
+  Approves an image for public viewing.
+
+  This will make the image visible to users and update necessary statistics.
+
+  ## Examples
+
+      iex> approve_image(image)
+      {:ok, %Image{}}
+  """
   def approve_image(image) do
     image
     |> Repo.preload(:user)
@@ -197,6 +207,18 @@ defmodule Philomena.Images do
 
   defp maybe_suggest_user_verification(_user), do: false
 
+  @doc """
+  Counts the number of images pending approval that a user can moderate.
+
+  ## Examples
+
+      iex> count_pending_approvals(admin)
+      42
+
+      iex> count_pending_approvals(user)
+      nil
+
+  """
   def count_pending_approvals(user) do
     if Canada.Can.can?(user, :approve, %Image{}) do
       Image
@@ -208,12 +230,36 @@ defmodule Philomena.Images do
     end
   end
 
+  @doc """
+  Marks the given image as the current featured image.
+
+  ## Examples
+
+      iex> feature_image(user, image)
+      {:ok, %ImageFeature{}}
+
+  """
   def feature_image(featurer, %Image{} = image) do
     %ImageFeature{user_id: featurer.id, image_id: image.id}
     |> ImageFeature.changeset(%{})
     |> Repo.insert()
   end
 
+  @doc """
+  Destroys the contents of an image (hard deletion) by marking it as hidden
+  and deleting up associated files.
+
+  This will:
+  1. Mark the image as removed in the database
+  2. Purge associated files
+  3. Remove thumbnails
+
+  ## Examples
+
+      iex> destroy_image(image)
+      {:ok, %Image{}}
+
+  """
   def destroy_image(%Image{} = image) do
     image
     |> Image.remove_image_changeset()
@@ -230,36 +276,91 @@ defmodule Philomena.Images do
     end
   end
 
+  @doc """
+  Locks or unlocks comments on an image.
+
+  ## Examples
+
+      iex> lock_comments(image, true)
+      {:ok, %Image{}}
+
+  """
   def lock_comments(%Image{} = image, locked) do
     image
     |> Image.lock_comments_changeset(locked)
     |> Repo.update()
   end
 
+  @doc """
+  Locks or unlocks the description of an image.
+
+  ## Examples
+
+      iex> lock_description(image, true)
+      {:ok, %Image{}}
+
+  """
   def lock_description(%Image{} = image, locked) do
     image
     |> Image.lock_description_changeset(locked)
     |> Repo.update()
   end
 
+  @doc """
+  Locks or unlocks the tags on an image.
+
+  ## Examples
+
+      iex> lock_tags(image, true)
+      {:ok, %Image{}}
+
+  """
   def lock_tags(%Image{} = image, locked) do
     image
     |> Image.lock_tags_changeset(locked)
     |> Repo.update()
   end
 
+  @doc """
+  Removes the original SHA-512 hash from an image, allowing users to upload
+  the same file again.
+
+  ## Examples
+
+      iex> remove_hash(image)
+      {:ok, %Image{}}
+
+  """
   def remove_hash(%Image{} = image) do
     image
     |> Image.remove_hash_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Updates the scratchpad notes on an image.
+
+  ## Examples
+
+      iex> update_scratchpad(image, %{"scratchpad" => "New notes"})
+      {:ok, %Image{}}
+
+  """
   def update_scratchpad(%Image{} = image, attrs) do
     image
     |> Image.scratchpad_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Removes all source change history for an image.
+
+  ## Examples
+
+      iex> remove_source_history(image)
+      {:ok, %Image{}}
+
+  """
   def remove_source_history(%Image{} = image) do
     image
     |> Repo.preload(:source_changes)
@@ -267,17 +368,49 @@ defmodule Philomena.Images do
     |> Repo.update()
   end
 
+  @doc """
+  Repairs an image by regenerating its thumbnails.
+  Returns the image struct unchanged, for use in a pipeline.
+
+  This will:
+  1. Mark the image as needing thumbnail regeneration
+  2. Queue the thumbnail generation job
+
+  ## Examples
+
+      iex> repair_image(image)
+      %Image{}
+
+  """
   def repair_image(%Image{} = image) do
     Image
     |> where(id: ^image.id)
     |> Repo.update_all(set: [thumbnails_generated: false, processed: false])
 
     Exq.enqueue(Exq, queue(image.image_mime_type), ThumbnailWorker, [image.id])
+
+    image
   end
 
   defp queue("video/webm"), do: "videos"
   defp queue(_mime_type), do: "images"
 
+  @doc """
+  Updates the file content of an image.
+
+  This will:
+  1. Update the image metadata
+  2. Save the new file
+  3. Generate new thumbnails
+  4. Purge old files
+  5. Reindex the image
+
+  ## Examples
+
+      iex> update_file(image, %{"image" => upload})
+      {:ok, %Image{}}
+
+  """
   def update_file(%Image{} = image, attrs) do
     image
     |> Image.changeset(attrs)
@@ -316,12 +449,48 @@ defmodule Philomena.Images do
     |> Repo.update()
   end
 
+  @doc """
+  Updates an image's description.
+
+  ## Examples
+
+      iex> update_description(image, %{"description" => "New description"})
+      {:ok, %Image{}}
+
+  """
   def update_description(%Image{} = image, attrs) do
     image
     |> Image.description_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates an image's sources with attribution tracking.
+
+  Handles both added and removed sources. Automatically determines the user's
+  intended source changes based on the provided previous image state.
+
+  This will update the image's sources, create source change records
+  for tracking, and reindex the image.
+
+  ## Examples
+
+      iex> update_sources(
+      ...>   image,
+      ...>   %{attribution: attrs},
+      ...>   %{
+      ...>     "old_sources" => %{},
+      ...>     "sources" => %{"0" => "http://example.com"}
+      ...>    }
+      ...> )
+      {:ok,
+       %{
+         image: image,
+         added_source_changes: 1,
+         removed_source_changes: 0
+       }}
+
+  """
   def update_sources(%Image{} = image, attribution, attrs) do
     old_sources = attrs["old_sources"]
     new_sources = attrs["sources"]
@@ -383,6 +552,17 @@ defmodule Philomena.Images do
     }
   end
 
+  @doc """
+  Updates the locked tags on an image.
+
+  Locked tags can only be added or removed by privileged users.
+
+  ## Examples
+
+      iex> update_locked_tags(image, %{tag_input: "safe, validated"})
+      {:ok, %Image{}}
+
+  """
   def update_locked_tags(%Image{} = image, attrs) do
     new_tags = Tags.get_or_create_tags(attrs["tag_input"])
 
@@ -392,6 +572,33 @@ defmodule Philomena.Images do
     |> Repo.update()
   end
 
+  @doc """
+  Updates an image's tags with attribution tracking.
+
+  Handles both added and removed tags. Automatically determines the user's
+  intended tag changes based on the provided previous image state.
+
+  This will update the image's tags, create tag change records
+  for tracking, and reindex the image.
+
+  ## Examples
+
+      iex> update_tags(
+      ...>   image,
+      ...>   %{attribution: attrs},
+      ...>   %{
+      ...>     old_tag_input: "safe",
+      ...>     tag_input: "safe, cute"
+      ...>   }
+      ...> )
+      {:ok,
+       %{
+         image: image,
+         added_tag_changes: 1,
+         removed_tag_changes: 0
+       }}
+
+  """
   def update_tags(%Image{} = image, attribution, attrs) do
     old_tags = Tags.get_or_create_tags(attrs["old_tag_input"])
     new_tags = Tags.get_or_create_tags(attrs["tag_input"])
@@ -486,14 +693,27 @@ defmodule Philomena.Images do
     end
   end
 
+  @doc """
+  Updates the tag change tracking after committing updates to an image.
+
+  This updates the rate limit counters for total tag change count and rating change count
+  based on the changes made to the image.
+
+  ## Examples
+
+      iex> update_tag_change_limits_after_commit(image, %{user: user, ip: "127.0.0.1"})
+      :ok
+
+  """
   def update_tag_change_limits_after_commit(image, attribution) do
     rating_changed_count = if(image.ratings_changed, do: 1, else: 0)
     tag_changed_count = length(image.added_tags) + length(image.removed_tags)
     user = attribution[:user]
     ip = attribution[:ip]
 
-    Limits.update_tag_count_after_update(user, ip, tag_changed_count)
-    Limits.update_rating_count_after_update(user, ip, rating_changed_count)
+    :ok = Limits.update_tag_count_after_update(user, ip, tag_changed_count)
+    :ok = Limits.update_rating_count_after_update(user, ip, rating_changed_count)
+    :ok
   end
 
   defp tag_change_attributes(attribution, image, tag, added, user) do
@@ -518,18 +738,48 @@ defmodule Philomena.Images do
     }
   end
 
+  @doc """
+  Changes the uploader of an image.
+
+  ## Examples
+
+      iex> update_uploader(image, %{"username" => "Admin"})
+      {:ok, %Image{}}
+
+  """
   def update_uploader(%Image{} = image, attrs) do
     image
     |> Image.uploader_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates the anonymous status of an image.
+
+  ## Examples
+
+      iex> update_anonymous(image, %{"anonymous" => "true"})
+      {:ok, %Image{}}
+
+  """
   def update_anonymous(%Image{} = image, attrs) do
     image
     |> Image.anonymous_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates the hide reason for an image.
+
+  ## Examples
+
+      iex> update_hide_reason(image, %{hide_reason: "Duplicate of #1234"})
+      {:ok, %Image{}}
+
+      iex> update_hide_reason(image, %{hide_reason: ""})
+      {:ok, %Image{}}
+
+  """
   def update_hide_reason(%Image{} = image, attrs) do
     image
     |> Image.hide_reason_changeset(attrs)
@@ -545,6 +795,28 @@ defmodule Philomena.Images do
     end
   end
 
+  @doc """
+  Hides an image from public view.
+
+  This will:
+  1. Mark the image as hidden
+  2. Close all reports and duplicate reports
+  3. Delete all gallery interactions containing the image
+  4. Decrement all tag counts with the image
+  5. Hide the image's thumbnails and purge them from the CDN
+  6. Reindex the image and all of its comments
+
+  ## Examples
+
+      iex> hide_image(image, moderator, %{reason: "Rule violation"})
+      {:ok,
+       %{
+         image: image,
+         tags: tags,
+         reports: {count, reports}
+       }}
+
+  """
   def hide_image(%Image{} = image, user, attrs) do
     duplicate_reports =
       DuplicateReport
@@ -560,6 +832,33 @@ defmodule Philomena.Images do
     |> process_after_hide()
   end
 
+  @doc """
+  Merges one image into another, combining their metadata and content.
+
+  This will:
+  1. Hide the source image
+  2. Update first_seen_at timestamp
+  3. Copy tags to the target image
+  4. Migrate sources, comments, subscriptions and interactions
+  5. Send merge notifications
+  6. Reindex both images and all of the comments
+
+  ## Parameters
+  - multi: Optional `m:Ecto.Multi` for transaction handling
+  - image: The source image to merge from
+  - duplicate_of_image: The target image to merge into
+  - user: The user performing the merge
+
+  ## Examples
+
+      iex> merge_image(nil, source_image, target_image, moderator)
+      {:ok,
+       %{
+         image: image,
+         tags: tags
+       }}
+
+  """
   def merge_image(multi \\ nil, %Image{} = image, duplicate_of_image, user) do
     multi = multi || Multi.new()
 
@@ -675,6 +974,26 @@ defmodule Philomena.Images do
     {:ok, image}
   end
 
+  @doc """
+  Unhides an image, making it visible to users again.
+
+  This will:
+  1. Remove the hidden status from the image
+  2. Increment tag counts
+  3. Unhide thumbnails
+  4. Reindex the image and related content
+
+  Returns {:ok, image} if successful, or returns the image unchanged if it's not hidden.
+
+  ## Examples
+
+      iex> unhide_image(hidden_image)
+      {:ok, %Image{hidden_from_users: false}}
+
+      iex> unhide_image(visible_image)
+      {:ok, %Image{}}
+
+  """
   def unhide_image(%Image{hidden_from_users: true} = image) do
     key = image.hidden_image_key
 
@@ -711,6 +1030,24 @@ defmodule Philomena.Images do
 
   def unhide_image(image), do: {:ok, image}
 
+  @doc """
+  Performs a batch update on multiple images, adding and removing tags.
+
+  This function efficiently updates tags for multiple images at once,
+  handling tag changes, tag counts, and reindexing in a single transaction.
+
+  ## Parameters
+  - image_ids: List of image IDs to update
+  - added_tags: List of tags to add to all images
+  - removed_tags: List of tags to remove from all images
+  - tag_change_attributes: Attributes tag changes are created with
+
+  ## Examples
+
+      iex> batch_update([1, 2], [tag1], [tag2], %{user_id: user.id})
+      {:ok, ...}
+
+  """
   def batch_update(image_ids, added_tags, removed_tags, tag_change_attributes) do
     image_ids =
       Image
@@ -828,24 +1165,65 @@ defmodule Philomena.Images do
     Image.changeset(image, %{})
   end
 
+  @doc """
+  Updates image search indices when a user's name changes.
+
+  ## Examples
+
+      iex> user_name_reindex("old_username", "new_username")
+      :ok
+
+  """
   def user_name_reindex(old_name, new_name) do
     data = ImageIndex.user_name_update_by_query(old_name, new_name)
 
     Search.update_by_query(Image, data.query, data.set_replacements, data.replacements)
   end
 
+  @doc """
+  Queues a single image for search index updates.
+  Returns the image struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_image(image)
+      %Image{}
+
+  """
   def reindex_image(%Image{} = image) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Images", "id", [image.id]])
 
     image
   end
 
+  @doc """
+  Queues all listed image IDs for search index updates.
+  Returns the list unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_images([1, 2, 3])
+      [1, 2, 3]
+
+  """
   def reindex_images(image_ids) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Images", "id", image_ids])
 
     image_ids
   end
 
+  @doc """
+  Returns the preload configuration for image indexing.
+
+  Specifies which associations should be preloaded when indexing images,
+  optimizing the queries for better performance.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [sources: query, user: query, ...]
+
+  """
   def indexing_preloads do
     user_query = select(User, [u], map(u, [:id, :name]))
     sources_query = select(Source, [s], map(s, [:image_id, :source]))
@@ -869,6 +1247,19 @@ defmodule Philomena.Images do
     ]
   end
 
+  @doc """
+  Performs a search reindex operation on images matching the given criteria.
+
+  ## Parameters
+  - column: The database column to filter on (e.g., :id)
+  - condition: A list of values to match against the column
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      :ok
+
+  """
   def perform_reindex(column, condition) do
     Image
     |> preload(^indexing_preloads())
@@ -876,6 +1267,17 @@ defmodule Philomena.Images do
     |> Search.reindex(Image)
   end
 
+  @doc """
+  Purges image files from the CDN.
+
+  Enqueues a job to purge both visible and hidden thumbnail paths for the given image.
+
+  ## Examples
+
+      iex> purge_files(image, "hidden_key")
+      :ok
+
+  """
   def purge_files(image, hidden_key) do
     files =
       if is_nil(hidden_key) do
@@ -888,6 +1290,17 @@ defmodule Philomena.Images do
     Exq.enqueue(Exq, "indexing", ImagePurgeWorker, [files])
   end
 
+  @doc """
+  Executes the actual purge operation for image files.
+
+  Calls the system purge-cache command to remove the specified files from the CDN cache.
+
+  ## Examples
+
+      iex> perform_purge(["file1.jpg", "file2.jpg"])
+      :ok
+
+  """
   def perform_purge(files) do
     {_out, 0} = System.cmd("purge-cache", [Jason.encode!(%{files: files})])
 
@@ -896,6 +1309,29 @@ defmodule Philomena.Images do
 
   alias Philomena.Images.Subscription
 
+  @doc """
+  Migrates subscriptions and notifications from one image to another.
+
+  This function is used during image merging to transfer all subscriptions
+  and notifications from the source image to the target image. It handles:
+
+  1. User subscriptions
+  2. Comment notifications
+  3. Merge notifications
+
+  Returns `{:ok, {comment_notification_count, merge_notification_count}}`.
+
+  ## Parameters
+
+    - source: The source image to migrate from
+    - target: The target image to migrate to
+
+  ## Examples
+
+      iex> migrate_subscriptions(source_image, target_image)
+      {:ok, {5, 2}}
+
+  """
   def migrate_subscriptions(source, target) do
     subscriptions =
       Subscription
@@ -941,6 +1377,29 @@ defmodule Philomena.Images do
     {:ok, {comment_notification_count, merge_notification_count}}
   end
 
+  @doc """
+  Migrates source URLs from one image to another.
+
+  This function is used during image merging to combine source URLs from both images.
+  It will:
+
+  1. Combine sources from both images
+  2. Remove duplicates
+  3. Take up to 15 sources (the system limit)
+  4. Update the target image with the combined sources
+
+  Returns the result of updating the target image with the combined sources.
+
+  ## Parameters
+  - source: The source image containing sources to migrate
+  - target: The target image to receive the combined sources
+
+  ## Examples
+
+      iex> migrate_sources(source_image, target_image)
+      {:ok, %Image{}}
+
+  """
   def migrate_sources(source, target) do
     sources =
       (source.sources ++ target.sources)
diff --git a/lib/philomena/interactions.ex b/lib/philomena/interactions.ex
index 8da603ba..8d2d9eca 100644
--- a/lib/philomena/interactions.ex
+++ b/lib/philomena/interactions.ex
@@ -8,6 +8,19 @@ defmodule Philomena.Interactions do
   alias Philomena.Repo
   alias Ecto.Multi
 
+  @doc """
+  Gets all interactions for a list of images for a given user.
+
+  Returns an empty list if no user is provided. Otherwise returns a list of maps containing:
+  - image_id: The ID of the image
+  - user_id: The ID of the user
+  - interaction_type: One of "hidden", "faved", or "voted"
+  - value: For votes, either "up" or "down". Empty string for other interaction types.
+
+  ## Parameters
+    * images - List of images or image IDs to get interactions for
+    * user - The user to get interactions for, or nil
+  """
   def user_interactions(_images, nil),
     do: []
 
@@ -71,6 +84,18 @@ defmodule Philomena.Interactions do
     |> Repo.all()
   end
 
+  @doc """
+  Migrates all interactions from one image to another.
+
+  Copies all hides, faves, and votes from the source image to the target image.
+  Updates the target image's counters to reflect the new interactions.
+  All operations are performed in a single transaction.
+
+  ## Parameters
+    * source - The source Image struct to copy interactions from
+    * target - The target Image struct to copy interactions to
+
+  """
   def migrate_interactions(source, target) do
     now = DateTime.utc_now(:second)
     source = Repo.preload(source, [:hiders, :favers, :upvoters, :downvoters])
diff --git a/lib/philomena/posts.ex b/lib/philomena/posts.ex
index 70cd5e94..70b69631 100644
--- a/lib/philomena/posts.ex
+++ b/lib/philomena/posts.ex
@@ -111,6 +111,23 @@ defmodule Philomena.Posts do
     Notifications.create_forum_post_notification(post.user, topic, post)
   end
 
+  @doc """
+  Creates a system report for non-approved posts containing external images.
+  Returns false for already approved posts.
+
+  ## Returns
+  - `false`: If the post is already approved
+  - `{:ok, %Report{}}`: If a system report was created
+
+  ## Examples
+
+      iex> report_non_approved(approved_post)
+      false
+
+      iex> report_non_approved(unapproved_post)
+      {:ok, %Report{}}
+
+  """
   def report_non_approved(%Post{approved: true}), do: false
 
   def report_non_approved(post) do
@@ -176,6 +193,20 @@ defmodule Philomena.Posts do
     Repo.delete(post)
   end
 
+  @doc """
+  Hides a post and handles associated reports.
+
+  ## Parameters
+  - post: The post to hide
+  - attrs: Attributes for the hide operation
+  - user: The user performing the hide action
+
+  ## Examples
+
+      iex> hide_post(post, %{staff_note: "Rule violation"}, user)
+      {:ok, %Post{}}
+
+  """
   def hide_post(%Post{} = post, attrs, user) do
     report_query = Reports.close_report_query({"Post", post.id}, user)
 
@@ -209,6 +240,15 @@ defmodule Philomena.Posts do
     end
   end
 
+  @doc """
+  Unhides a previously hidden post.
+
+  ## Examples
+
+      iex> unhide_post(post)
+      {:ok, %Post{}}
+
+  """
   def unhide_post(%Post{} = post) do
     post
     |> Post.unhide_changeset()
@@ -216,6 +256,15 @@ defmodule Philomena.Posts do
     |> reindex_after_update()
   end
 
+  @doc """
+  Marks a post as destroyed and removes its text (hard deletion).
+
+  ## Examples
+
+      iex> destroy_post(post)
+      {:ok, %Post{}}
+
+  """
   def destroy_post(%Post{} = post) do
     post
     |> Post.destroy_changeset()
@@ -223,6 +272,20 @@ defmodule Philomena.Posts do
     |> reindex_after_update()
   end
 
+  @doc """
+  Approves a post, closes associated reports, and increments the user forum
+  posts count.
+
+  ## Parameters
+  - post: The post to approve
+  - user: The user performing the approval
+
+  ## Examples
+
+      iex> approve_comment(post, user)
+      {:ok, %Post{}}
+
+  """
   def approve_post(%Post{} = post, user) do
     report_query = Reports.close_report_query({"Post", post.id}, user)
     post = Post.approve_changeset(post)
@@ -257,6 +320,15 @@ defmodule Philomena.Posts do
     Post.changeset(post, %{})
   end
 
+  @doc """
+  Updates post search indices when a user's name changes.
+
+  ## Examples
+
+      iex> user_name_reindex("old_username", "new_username")
+      :ok
+
+  """
   def user_name_reindex(old_name, new_name) do
     data = PostIndex.user_name_update_by_query(old_name, new_name)
 
@@ -273,12 +345,31 @@ defmodule Philomena.Posts do
     result
   end
 
+  @doc """
+  Queues a single post for search index updates.
+  Returns the post struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_comment(post)
+      %Post{}
+
+  """
   def reindex_post(%Post{} = post) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Posts", "id", [post.id]])
 
     post
   end
 
+  @doc """
+  Provides preload queries for post indexing operations.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [user: user_query, topic: topic_query]
+
+  """
   def indexing_preloads do
     user_query = select(User, [u], map(u, [:id, :name]))
 
@@ -293,6 +384,22 @@ defmodule Philomena.Posts do
     ]
   end
 
+  @doc """
+  Performs a search reindex operation on posts matching the given criteria.
+
+  ## Parameters
+  - column: The database column to filter on (e.g., :id, :topic_id)
+  - condition: A list of values to match against the column
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      :ok
+
+      iex> perform_reindex(:topic_id, [123])
+      :ok
+
+  """
   def perform_reindex(column, condition) do
     Post
     |> preload(^indexing_preloads())
diff --git a/lib/philomena/slug.ex b/lib/philomena/slug.ex
index 61f2baea..51cb4acb 100644
--- a/lib/philomena/slug.ex
+++ b/lib/philomena/slug.ex
@@ -1,29 +1,32 @@
 defmodule Philomena.Slug do
-  # Generates a URL-safe slug from a string by removing nonessential
-  # information from it.
-  #
-  # The process for this is as follows:
-  #
-  # 1. Remove non-ASCII or non-printable characters.
-  #
-  # 2. Replace any runs of non-alphanumeric characters that were allowed
-  #    through previously with hyphens.
-  #
-  # 3. Remove any starting or ending hyphens.
-  #
-  # 4. Convert all characters to their lowercase equivalents.
-  #
-  # This method makes no guarantee of creating unique slugs for unique inputs.
-  # In addition, for certain inputs, it will return empty strings.
-  #
-  # Example
-  #
-  #   destructive_slug("Time-Wasting Thread 3.0 (SFW - No Explicit/Grimdark)")
-  #   #=> "time-wasting-thread-3-0-sfw-no-explicit-grimdark"
-  #
-  #   destructive_slug("~`!@#$%^&*()-_=+[]{};:'\" <>,./?")
-  #   #=> ""
-  #
+  @moduledoc """
+  URL-safe string shortening.
+  """
+
+  @doc """
+  Generates a URL-safe slug from a string by removing nonessential
+  information from it.
+
+  The process for this is as follows:
+
+  1. Remove non-ASCII or non-printable characters.
+  2. Replace any runs of non-alphanumeric characters that were allowed
+     through previously with hyphens.
+  3. Remove any starting or ending hyphens.
+  4. Convert all characters to their lowercase equivalents.
+
+  This method makes no guarantee of creating unique slugs for unique inputs.
+  In addition, for certain inputs, it will return empty strings.
+
+  ## Example
+
+      iex> destructive_slug("Time-Wasting Thread 3.0 (SFW - No Explicit/Grimdark)")
+      "time-wasting-thread-3-0-sfw-no-explicit-grimdark"
+
+      iex> destructive_slug("~`!@#$%^&*()-_=+[]{};:'\" <>,./?")
+      ""
+
+  """
   @spec destructive_slug(String.t()) :: String.t()
   def destructive_slug(input) when is_binary(input) do
     input
@@ -39,6 +42,11 @@ defmodule Philomena.Slug do
 
   def destructive_slug(_input), do: ""
 
+  @doc """
+  Generates a reversible slug from a string by replacing certain characters
+  with escaped (not URL-encoded) equivalents.
+  """
+  @spec slug(String.t()) :: String.t()
   def slug(string) when is_binary(string) do
     string
     |> String.replace("-", "-dash-")
diff --git a/lib/philomena/tags.ex b/lib/philomena/tags.ex
index d6c6898a..7a9a79b6 100644
--- a/lib/philomena/tags.ex
+++ b/lib/philomena/tags.ex
@@ -24,6 +24,19 @@ defmodule Philomena.Tags do
   alias Philomena.DnpEntries.DnpEntry
   alias Philomena.Channels.Channel
 
+  @doc """
+  Gets existing tags or creates new ones from a tag list string.
+
+  Takes a string of comma-separated tag names, parses it into individual tags,
+  and either retrieves existing tags or creates new ones for tags that don't exist.
+  Also handles tag aliases by returning the aliased tag instead of the alias.
+
+  ## Examples
+
+      iex> get_or_create_tags("safe, cute, pony")
+      [%Tag{name: "safe"}, %Tag{name: "cute"}, %Tag{name: "pony"}]
+
+  """
   @spec get_or_create_tags(String.t()) :: list()
   def get_or_create_tags(tag_list) do
     tag_names = Tag.parse_tag_list(tag_list)
@@ -174,6 +187,18 @@ defmodule Philomena.Tags do
     end
   end
 
+  @doc """
+  Updates a tag's associated image.
+
+  Takes a tag and image upload attributes, analyzes the upload,
+  persists it, and removes the old tag image if successful.
+
+  ## Examples
+
+      iex> update_tag_image(tag, %{"image" => upload})
+      {:ok, %Tag{}}
+
+  """
   def update_tag_image(%Tag{} = tag, attrs) do
     tag
     |> Uploader.analyze_upload(attrs)
@@ -190,6 +215,17 @@ defmodule Philomena.Tags do
     end
   end
 
+  @doc """
+  Removes a tag's associated image.
+
+  Removes the image from the tag and deletes the persisted file.
+
+  ## Examples
+
+      iex> remove_tag_image(tag)
+      {:ok, %Tag{}}
+
+  """
   def remove_tag_image(%Tag{} = tag) do
     tag
     |> Tag.remove_image_changeset()
@@ -223,6 +259,18 @@ defmodule Philomena.Tags do
     {:ok, tag}
   end
 
+  @doc """
+  Performs the actual deletion of a tag.
+
+  Removes the tag from the database, deletes its search index,
+  and reindexes all images that were tagged with it.
+
+  ## Examples
+
+      iex> perform_delete(123)
+      :ok
+
+  """
   def perform_delete(tag_id) do
     tag = get_tag!(tag_id)
 
@@ -243,6 +291,19 @@ defmodule Philomena.Tags do
     |> Search.reindex(Image)
   end
 
+  @doc """
+  Creates an alias from one tag to another.
+
+  Takes a source tag and target tag name, creating an alias relationship
+  where the source tag becomes an alias of the target tag. Once the alias
+  is created, a job is queued to finish processing the alias.
+
+  ## Examples
+
+      iex> alias_tag(source_tag, %{"target_tag" => "destination"})
+      {:ok, %Tag{}}
+
+  """
   def alias_tag(%Tag{} = tag, attrs) do
     target_tag = Repo.get_by(Tag, name: String.downcase(attrs["target_tag"]))
 
@@ -261,6 +322,19 @@ defmodule Philomena.Tags do
     end
   end
 
+  @doc """
+  Performs the actual tag aliasing operation.
+
+  Transfers all associations from the source tag to the target tag,
+  including image taggings, filters, user watches, and other relationships.
+  Updates counters and reindexes affected records.
+
+  ## Examples
+
+      iex> perform_alias(123, 456)
+      :ok
+
+  """
   def perform_alias(tag_id, target_tag_id) do
     tag = get_tag!(tag_id)
     target_tag = get_tag!(target_tag_id)
@@ -315,14 +389,36 @@ defmodule Philomena.Tags do
     # Finally, reindex
     reindex_tag_images(target_tag)
     reindex_tags([tag, target_tag])
+
+    :ok
   end
 
+  @doc """
+  Enqueues reindexing of all images associated with a tag.
+
+  ## Examples
+
+      iex> reindex_tag_images(tag)
+      {:ok, %Tag{}}
+
+  """
   def reindex_tag_images(%Tag{} = tag) do
     Exq.enqueue(Exq, "indexing", TagReindexWorker, [tag.id])
 
     {:ok, tag}
   end
 
+  @doc """
+  Performs reindexing of all images associated with a tag.
+
+  Updates the tag's image count to reflect the current number of non-hidden images,
+  then reindexes all associated images and filters that reference this tag.
+
+  ## Examples
+
+      iex> perform_reindex_images(123)
+
+  """
   def perform_reindex_images(tag_id) do
     tag = get_tag!(tag_id)
 
@@ -351,12 +447,32 @@ defmodule Philomena.Tags do
     |> Search.reindex(Filter)
   end
 
+  @doc """
+  Enqueues removal of a tag alias.
+
+  ## Examples
+
+      iex> unalias_tag(tag)
+      {:ok, %Tag{}}
+
+  """
   def unalias_tag(%Tag{} = tag) do
     Exq.enqueue(Exq, "indexing", TagUnaliasWorker, [tag.id])
 
     {:ok, tag}
   end
 
+  @doc """
+  Performs removal of a tag alias.
+
+  Removes the alias relationship between two tags and reindexes
+  the images of the formerly aliased tag.
+
+  ## Examples
+
+      iex> perform_unalias(123)
+      {:ok, %Tag{}}
+  """
   def perform_unalias(tag_id) do
     tag = get_tag!(tag_id)
     former_alias = Repo.preload(tag, :aliased_tag).aliased_tag
@@ -389,6 +505,18 @@ defmodule Philomena.Tags do
     |> Repo.update_all([])
   end
 
+  @doc """
+  Copies tags from one image to another.
+
+  Creates new taggings on the target image for all tags present on the source image,
+  updates tag counters, and returns the list of copied tags.
+
+  ## Examples
+
+      iex> copy_tags(source_image, target_image)
+      [%Tag{}, ...]
+
+  """
   def copy_tags(source, target) do
     # Ecto bug:
     # ** (DBConnection.EncodeError) Postgrex expected a binary, got 5.
@@ -437,22 +565,66 @@ defmodule Philomena.Tags do
     Tag.changeset(tag, %{})
   end
 
+  @doc """
+  Queues a single tag for search index updates.
+  Returns the tag struct unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_tag(tag)
+      %Tag{}
+
+  """
   def reindex_tag(%Tag{} = tag) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Tags", "id", [tag.id]])
 
     tag
   end
 
+  @doc """
+  Queues a list of tags for search index updates.
+  Returns the list of tags unchanged, for use in a pipeline.
+
+  ## Examples
+
+      iex> reindex_tags([%Tag{}, %Tag{}, ...])
+      [%Tag{}, %Tag{}, ...]
+
+  """
   def reindex_tags(tags) do
     Exq.enqueue(Exq, "indexing", IndexWorker, ["Tags", "id", Enum.map(tags, & &1.id)])
 
     tags
   end
 
+  @doc """
+  Returns the list of associations to preload for tag indexing.
+
+  ## Examples
+
+      iex> indexing_preloads()
+      [:aliased_tag, :aliases, :implied_tags, :implied_by_tags]
+
+  """
   def indexing_preloads do
     [:aliased_tag, :aliases, :implied_tags, :implied_by_tags]
   end
 
+  @doc """
+  Performs reindexing of tags based on a column condition.
+
+  Takes a column name and a list of values to match against that column,
+  then reindexes all matching tags.
+
+  ## Examples
+
+      iex> perform_reindex(:id, [1, 2, 3])
+      {:ok, []}
+
+      iex> perform_reindex(:name, ["safe", "suggestive"])
+      {:ok, []}
+
+  """
   def perform_reindex(column, condition) do
     Tag
     |> preload(^indexing_preloads())
diff --git a/lib/philomena/topics.ex b/lib/philomena/topics.ex
index 38a5d602..1f7c578e 100644
--- a/lib/philomena/topics.ex
+++ b/lib/philomena/topics.ex
@@ -138,26 +138,71 @@ defmodule Philomena.Topics do
     Topic.changeset(topic, %{})
   end
 
+  @doc """
+  Makes a topic sticky, appearing at the top of its forum.
+
+  ## Examples
+
+      iex> stick_topic(topic)
+      {:ok, %Topic{}}
+
+  """
   def stick_topic(topic) do
     Topic.stick_changeset(topic)
     |> Repo.update()
   end
 
+  @doc """
+  Removes sticky status from a topic.
+
+  ## Examples
+
+      iex> unstick_topic(topic)
+      {:ok, %Topic{}}
+
+  """
   def unstick_topic(topic) do
     Topic.unstick_changeset(topic)
     |> Repo.update()
   end
 
+  @doc """
+  Locks a topic to prevent further posting.
+
+  ## Examples
+
+      iex> lock_topic(topic, %{"lock_reason" => "Off topic"}, user)
+      {:ok, %Topic{}}
+
+  """
   def lock_topic(%Topic{} = topic, attrs, user) do
     Topic.lock_changeset(topic, attrs, user)
     |> Repo.update()
   end
 
+  @doc """
+  Unlocks a topic to allow posting again.
+
+  ## Examples
+
+      iex> unlock_topic(topic)
+      {:ok, %Topic{}}
+
+  """
   def unlock_topic(%Topic{} = topic) do
     Topic.unlock_changeset(topic)
     |> Repo.update()
   end
 
+  @doc """
+  Moves a topic to a different forum, updating post counts for both forums.
+
+  ## Examples
+
+      iex> move_topic(topic, 123)
+      {:ok, %{topic: %Topic{}}}
+
+  """
   def move_topic(topic, new_forum_id) do
     old_forum_id = topic.forum_id
     topic_changes = Topic.move_changeset(topic, new_forum_id)
@@ -183,6 +228,15 @@ defmodule Philomena.Topics do
     |> Repo.transaction()
   end
 
+  @doc """
+  Hides a topic and updates related forum data.
+
+  ## Examples
+
+      iex> hide_topic(topic, "Violates rules", moderator)
+      {:ok, %Topic{}}
+
+  """
   def hide_topic(topic, deletion_reason, user) do
     topic_changes = Topic.hide_changeset(topic, deletion_reason, user)
 
@@ -205,11 +259,29 @@ defmodule Philomena.Topics do
     end
   end
 
+  @doc """
+  Unhides a previously hidden topic.
+
+  ## Examples
+
+      iex> unhide_topic(topic)
+      {:ok, %Topic{}}
+
+  """
   def unhide_topic(topic) do
     Topic.unhide_changeset(topic)
     |> Repo.update()
   end
 
+  @doc """
+  Updates a topic's title.
+
+  ## Examples
+
+      iex> update_topic_title(topic, %{"title" => "New Title"})
+      {:ok, %Topic{}}
+
+  """
   def update_topic_title(topic, attrs) do
     topic
     |> Topic.title_changeset(attrs)
diff --git a/lib/philomena/users.ex b/lib/philomena/users.ex
index 575552aa..7c002257 100644
--- a/lib/philomena/users.ex
+++ b/lib/philomena/users.ex
@@ -273,6 +273,12 @@ defmodule Philomena.Users do
 
   @doc """
   Unconditionally unlocks the given user.
+
+  ## Examples
+
+      iex> unlock_user(user)
+      {:ok, %User{}}
+
   """
   def unlock_user(user) do
     user
@@ -369,6 +375,20 @@ defmodule Philomena.Users do
     load_with_roles(query)
   end
 
+  @doc """
+  Checks if a TOTP token is valid for a given user.
+
+  Returns false if no user is provided.
+
+  ## Examples
+
+      iex> user_totp_token_valid?(user, "123456")
+      true
+
+      iex> user_totp_token_valid?(nil, "123456")
+      false
+
+  """
   def user_totp_token_valid?(nil, _token) do
     false
   end
@@ -503,6 +523,15 @@ defmodule Philomena.Users do
     end
   end
 
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking user changes.
+
+  ## Examples
+
+      iex> change_user(user)
+      %Ecto.Changeset{data: %User{}}
+
+  """
   def change_user(%User{} = user) do
     User.changeset(user, %{})
   end
@@ -544,30 +573,84 @@ defmodule Philomena.Users do
   defp clean_roles(nil), do: []
   defp clean_roles(roles), do: Enum.filter(roles, &("" != &1))
 
+  @doc """
+  Updates a user's spoiler type settings.
+
+  ## Examples
+
+      iex> update_spoiler_type(user, %{spoiler_type: "click"})
+      {:ok, %User{}}
+
+      iex> update_spoiler_type(user, %{spoiler_type: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
   def update_spoiler_type(%User{} = user, attrs) do
     user
     |> User.spoiler_type_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates a user's general settings.
+
+  ## Examples
+
+      iex> update_settings(user, %{"theme" => "dark"})
+      {:ok, %User{}}
+
+      iex> update_settings(user, %{"theme" => bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
   def update_settings(%User{} = user, attrs) do
     user
     |> User.settings_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates a user's profile description and personal title.
+
+  ## Examples
+
+      iex> update_description(user, %{"description" => "Hello world"})
+      {:ok, %User{}}
+
+      iex> update_description(user, %{"personal_title" => "Site Admin"})
+      {:error, %Ecto.Changeset{}}
+
+  """
   def update_description(%User{} = user, attrs) do
     user
     |> User.description_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Updates a user's moderation scratchpad content.
+
+  ## Examples
+
+      iex> update_scratchpad(user, %{"scratchpad" => "My notes"})
+      {:ok, %User{}}
+
+  """
   def update_scratchpad(%User{} = user, attrs) do
     user
     |> User.scratchpad_changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Adds a tag to a user's watched tags list.
+
+  ## Examples
+
+      iex> watch_tag(user, tag)
+      {:ok, %User{}}
+
+  """
   def watch_tag(%User{} = user, tag) do
     watched_tag_ids = Enum.uniq([tag.id | user.watched_tag_ids])
 
@@ -576,6 +659,15 @@ defmodule Philomena.Users do
     |> Repo.update()
   end
 
+  @doc """
+  Removes a tag from a user's watched tags list.
+
+  ## Examples
+
+      iex> unwatch_tag(user, tag)
+      {:ok, %User{}}
+
+  """
   def unwatch_tag(%User{} = user, tag) do
     watched_tag_ids = user.watched_tag_ids -- [tag.id]
 
@@ -584,6 +676,17 @@ defmodule Philomena.Users do
     |> Repo.update()
   end
 
+  @doc """
+  Updates a user's avatar with the provided file.
+
+  Handles file analysis and persistence.
+
+  ## Examples
+
+      iex> update_avatar(user, %{"avatar" => upload})
+      {:ok, %User{}}
+
+  """
   def update_avatar(%User{} = user, attrs) do
     user
     |> Uploader.analyze_upload(attrs)
@@ -600,6 +703,15 @@ defmodule Philomena.Users do
     end
   end
 
+  @doc """
+  Removes a user's avatar.
+
+  ## Examples
+
+      iex> remove_avatar(user)
+      {:ok, %User{}}
+
+  """
   def remove_avatar(%User{} = user) do
     user
     |> User.remove_avatar_changeset()
@@ -615,6 +727,17 @@ defmodule Philomena.Users do
     end
   end
 
+  @doc """
+  Updates a user's name and records the change in history.
+
+  Triggers a background job to update references to the old username.
+
+  ## Examples
+
+      iex> update_name(user, %{"name" => "new_name"})
+      {:ok, %User{}}
+
+  """
   def update_name(user, user_params) do
     old_name = user.name
 
@@ -636,6 +759,17 @@ defmodule Philomena.Users do
     end
   end
 
+  @doc """
+  Updates all search engine references to a user's old name with their new name.
+
+  This is called as a background job after a user requests a name change.
+
+  ## Examples
+
+      iex> perform_rename("old_name", "new_name")
+      :ok
+
+  """
   def perform_rename(old_name, new_name) do
     Images.user_name_reindex(old_name, new_name)
     Comments.user_name_reindex(old_name, new_name)
@@ -645,36 +779,96 @@ defmodule Philomena.Users do
     Filters.user_name_reindex(old_name, new_name)
   end
 
+  @doc """
+  Reactivates a previously deactivated user account.
+
+  ## Examples
+
+      iex> reactivate_user(user)
+      {:ok, %User{}}
+
+  """
   def reactivate_user(%User{} = user) do
     user
     |> User.reactivate_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Deactivates a user account.
+
+  Takes a moderator who is recorded as performing the deactivation.
+
+  ## Examples
+
+      iex> deactivate_user(moderator, user)
+      {:ok, %User{}}
+
+  """
   def deactivate_user(moderator, %User{} = user) do
     user
     |> User.deactivate_changeset(moderator)
     |> Repo.update()
   end
 
+  @doc """
+  Generates a new API key for the user.
+
+  ## Examples
+
+      iex> reset_api_key(user)
+      {:ok, %User{}}
+
+  """
   def reset_api_key(%User{} = user) do
     user
     |> User.api_key_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Forces a specific filter on a user's account, which will be applied in
+  conjunction to the user's current filter.
+
+  ## Examples
+
+      iex> force_filter(user, %{"forced_filter_id" => 123})
+      {:ok, %User{}}
+
+      iex> force_filter(user, %{"forced_filter_id" => bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
   def force_filter(%User{} = user, user_params) do
     user
     |> User.force_filter_changeset(user_params)
     |> Repo.update()
   end
 
+  @doc """
+  Removes a forced filter from a user's account.
+
+  ## Examples
+
+      iex> unforce_filter(user)
+      {:ok, %User{}}
+
+  """
   def unforce_filter(%User{} = user) do
     user
     |> User.unforce_filter_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Clears a user's recent filter history.
+
+  ## Examples
+
+      iex> clear_recent_filters(user)
+      {:ok, %User{}}
+
+  """
   def clear_recent_filters(%User{} = user) do
     user
     |> User.clear_recent_filters_changeset()
@@ -688,18 +882,50 @@ defmodule Philomena.Users do
     |> setup_roles()
   end
 
+  @doc """
+  Marks a user as verified for the purposes of automatically approving uploads,
+  and posting images in comments/posts/messages without moderator review.
+
+  ## Examples
+
+      iex> verify_user(user)
+      {:ok, %User{}}
+
+  """
   def verify_user(%User{} = user) do
     user
     |> User.verify_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Unverifies a user, removing the automatic approval status.
+
+  ## Examples
+
+      iex> unverify_user(user)
+      {:ok, %User{}}
+
+  """
   def unverify_user(%User{} = user) do
     user
     |> User.unverify_changeset()
     |> Repo.update()
   end
 
+  @doc """
+  Erases all changes associated with a user account, removing all personal
+  data and anonymizing the account.
+
+  This is primarily intended for use with spam accounts or other situations
+  where all of a user's data should be removed from the system.
+
+  ## Examples
+
+      iex> erase_user(user, moderator)
+      {:ok, %User{}}
+
+  """
   def erase_user(%User{} = user, %User{} = moderator) do
     # Deactivate to prevent the user from racing these changes
     {:ok, user} = deactivate_user(moderator, user)