feat(brews): add filter paper to routes, views, CLI, and templates

- Add filter paper dropdown to brew form and gear category form
- Add custom deserializer for optional GearId from HTML forms
- Load filter papers in brews_page handler
- Show filter paper as subtext under brewer in brew list
- Add filter paper to timeline event details and brew-again forms
- Add --filter-paper-id flag to CLI brew add command

src/application/routes/brews.rs

@@ -2,7 +2,7 @@ use axum::Json;
 use axum::extract::{Query, State};
 use axum::http::{HeaderMap, StatusCode};
 use axum::response::{IntoResponse, Redirect, Response};
-use serde::Deserialize;
+use serde::{Deserialize, Deserializer};
 
 use super::macros::{define_delete_handler, define_enriched_get_handler};
 use crate::application::auth::AuthenticatedUser;
@@ -117,6 +117,22 @@ pub(crate) async fn brews_page(
         .map(GearOptionView::from)
         .collect();
 
+    // Load filter papers for dropdown (optional gear)
+    let filter_paper_request = ListRequest::show_all(GearSortKey::Make, SortDirection::Asc);
+    let filter_papers = state
+        .gear_repo
+        .list(
+            GearFilter::for_category(GearCategory::FilterPaper),
+            &filter_paper_request,
+        )
+        .await
+        .map_err(|err| map_app_error(AppError::from(err)))?;
+    let filter_paper_options: Vec<GearOptionView> = filter_papers
+        .items
+        .into_iter()
+        .map(GearOptionView::from)
+        .collect();
+
     let BrewPageData { brews, navigator } = load_brew_page(&state, request)
         .await
         .map_err(map_app_error)?;
@@ -130,12 +146,34 @@ pub(crate) async fn brews_page(
         bag_options,
         grinder_options,
         brewer_options,
+        filter_paper_options,
         navigator,
     };
 
     render_html(template).map(IntoResponse::into_response)
 }
 
+/// Deserializes an optional `GearId`, treating empty strings (from HTML forms) as None.
+fn deserialize_optional_gear_id<'de, D>(deserializer: D) -> Result<Option<GearId>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let value: Option<serde_json::Value> = Option::deserialize(deserializer)?;
+    match value {
+        None | Some(serde_json::Value::Null) => Ok(None),
+        Some(serde_json::Value::String(s)) if s.is_empty() => Ok(None),
+        Some(serde_json::Value::Number(n)) => n
+            .as_i64()
+            .map(|id| Some(GearId::new(id)))
+            .ok_or_else(|| serde::de::Error::custom("invalid gear id")),
+        Some(serde_json::Value::String(s)) => s
+            .parse::<i64>()
+            .map(|id| Some(GearId::new(id)))
+            .map_err(serde::de::Error::custom),
+        Some(_) => Err(serde::de::Error::custom("invalid gear id")),
+    }
+}
+
 #[derive(Debug, Deserialize)]
 pub(crate) struct NewBrewSubmission {
     bag_id: BagId,
@@ -143,6 +181,8 @@ pub(crate) struct NewBrewSubmission {
     grinder_id: GearId,
     grind_setting: f64,
     brewer_id: GearId,
+    #[serde(default, deserialize_with = "deserialize_optional_gear_id")]
+    filter_paper_id: Option<GearId>,
     water_volume: i32,
     water_temp: f64,
 }
@@ -170,6 +210,7 @@ impl NewBrewSubmission {
             grinder_id: self.grinder_id,
             grind_setting: self.grind_setting,
             brewer_id: self.brewer_id,
+            filter_paper_id: self.filter_paper_id,
             water_volume: self.water_volume,
             water_temp: self.water_temp,
         })
@@ -248,44 +289,54 @@ fn brew_timeline_event(enriched: &BrewWithDetails) -> NewTimelineEvent {
         "N/A".to_string()
     };
 
+    let mut details = vec![
+        TimelineEventDetail {
+            label: "Roaster".to_string(),
+            value: enriched.roaster_name.clone(),
+        },
+        TimelineEventDetail {
+            label: "Coffee".to_string(),
+            value: format!("{:.1}g", enriched.brew.coffee_weight),
+        },
+        TimelineEventDetail {
+            label: "Water".to_string(),
+            value: format!(
+                "{}ml @ {:.1}\u{00B0}C",
+                enriched.brew.water_volume, enriched.brew.water_temp
+            ),
+        },
+        TimelineEventDetail {
+            label: "Grinder".to_string(),
+            value: format!(
+                "{} @ {:.1}",
+                enriched.grinder_name, enriched.brew.grind_setting
+            ),
+        },
+        TimelineEventDetail {
+            label: "Brewer".to_string(),
+            value: enriched.brewer_name.clone(),
+        },
+    ];
+
+    if let Some(ref fp_name) = enriched.filter_paper_name {
+        details.push(TimelineEventDetail {
+            label: "Filter".to_string(),
+            value: fp_name.clone(),
+        });
+    }
+
+    details.push(TimelineEventDetail {
+        label: "Ratio".to_string(),
+        value: ratio,
+    });
+
     NewTimelineEvent {
         entity_type: "brew".to_string(),
         entity_id: enriched.brew.id.into_inner(),
         action: "brewed".to_string(),
         occurred_at: chrono::Utc::now(),
         title: enriched.roast_name.clone(),
-        details: vec![
+        details,
-            TimelineEventDetail {
-                label: "Roaster".to_string(),
-                value: enriched.roaster_name.clone(),
-            },
-            TimelineEventDetail {
-                label: "Coffee".to_string(),
-                value: format!("{:.1}g", enriched.brew.coffee_weight),
-            },
-            TimelineEventDetail {
-                label: "Water".to_string(),
-                value: format!(
-                    "{}ml @ {:.1}\u{00B0}C",
-                    enriched.brew.water_volume, enriched.brew.water_temp
-                ),
-            },
-            TimelineEventDetail {
-                label: "Grinder".to_string(),
-                value: format!(
-                    "{} @ {:.1}",
-                    enriched.grinder_name, enriched.brew.grind_setting
-                ),
-            },
-            TimelineEventDetail {
-                label: "Brewer".to_string(),
-                value: enriched.brewer_name.clone(),
-            },
-            TimelineEventDetail {
-                label: "Ratio".to_string(),
-                value: ratio,
-            },
-        ],
         tasting_notes: vec![],
         slug: Some(enriched.roast_slug.clone()),
         roaster_slug: Some(enriched.roaster_slug.clone()),
@@ -293,6 +344,10 @@ fn brew_timeline_event(enriched: &BrewWithDetails) -> NewTimelineEvent {
             bag_id: enriched.brew.bag_id.into_inner(),
             grinder_id: enriched.brew.grinder_id.into_inner(),
             brewer_id: enriched.brew.brewer_id.into_inner(),
+            filter_paper_id: enriched
+                .brew
+                .filter_paper_id
+                .map(crate::domain::ids::GearId::into_inner),
             coffee_weight: enriched.brew.coffee_weight,
             grind_setting: enriched.brew.grind_setting,
             water_volume: enriched.brew.water_volume,

src/presentation/cli/brews.rs

@@ -49,6 +49,10 @@ pub struct AddBrewCommand {
     #[arg(long)]
     pub brewer_id: i64,
 
+    /// ID of the filter paper to use (optional)
+    #[arg(long)]
+    pub filter_paper_id: Option<i64>,
+
     /// Volume of water in ml
     #[arg(long, default_value = "250")]
     pub water_volume: i32,
@@ -67,6 +71,7 @@ pub async fn add_brew(client: &BrewlogClient, command: AddBrewCommand) -> Result
             GearId::new(command.grinder_id),
             command.grind_setting,
             GearId::new(command.brewer_id),
+            command.filter_paper_id.map(GearId::new),
             command.water_volume,
             command.water_temp,
         )

src/presentation/web/templates.rs

@@ -135,6 +135,7 @@ pub struct BrewsTemplate {
     pub bag_options: Vec<BagOptionView>,
     pub grinder_options: Vec<GearOptionView>,
     pub brewer_options: Vec<GearOptionView>,
+    pub filter_paper_options: Vec<GearOptionView>,
     pub navigator: ListNavigator<BrewSortKey>,
 }
 

src/presentation/web/views.rs

@@ -421,6 +421,7 @@ pub struct TimelineBrewDataView {
     pub bag_id: i64,
     pub grinder_id: i64,
     pub brewer_id: i64,
+    pub filter_paper_id: Option<i64>,
     pub coffee_weight: f64,
     pub grind_setting: f64,
     pub water_volume: i32,
@@ -522,6 +523,7 @@ impl TimelineEventView {
             bag_id: bd.bag_id,
             grinder_id: bd.grinder_id,
             brewer_id: bd.brewer_id,
+            filter_paper_id: bd.filter_paper_id,
             coffee_weight: bd.coffee_weight,
             grind_setting: bd.grind_setting,
             water_volume: bd.water_volume,
@@ -621,6 +623,8 @@ pub struct BrewView {
     pub grind_setting: String,
     pub brewer_id: i64,
     pub brewer_name: String,
+    pub filter_paper_id: Option<i64>,
+    pub filter_paper_name: Option<String>,
     pub water_volume: String,
     pub water_temp: String,
     pub ratio: String,
@@ -656,6 +660,11 @@ impl BrewView {
             grind_setting: format!("{:.1}", brew.brew.grind_setting),
             brewer_id: brew.brew.brewer_id.into_inner(),
             brewer_name: brew.brewer_name,
+            filter_paper_id: brew
+                .brew
+                .filter_paper_id
+                .map(crate::domain::ids::GearId::into_inner),
+            filter_paper_name: brew.filter_paper_name,
             water_volume: format!("{}ml", brew.brew.water_volume),
             water_temp: format!("{:.1}\u{00B0}C", brew.brew.water_temp),
             ratio,

templates/brews.html

@@ -87,6 +87,17 @@
           </select>
         </label>
 
+        <!-- Filter Paper selector (optional) -->
+        <label class="flex flex-col gap-1 text-sm">
+          <span class="text-stone-700">Filter Paper</span>
+          <select name="filter_paper_id" class="input-field">
+            <option value="">None</option>
+            {% for fp in filter_paper_options %}
+            <option value="{{ fp.id }}">{{ fp.label }}</option>
+            {% endfor %}
+          </select>
+        </label>
+
         <!-- Coffee Weight with +/- buttons -->
         <div class="flex flex-col gap-1 text-sm">
           <span class="text-stone-700">Coffee (g) *</span>

templates/gear.html

@@ -47,6 +47,7 @@
             <option value="">Select a category</option>
             <option value="grinder">Grinder</option>
             <option value="brewer">Brewer</option>
+            <option value="filter_paper">Filter Paper</option>
           </select>
         </label>
         <label class="flex flex-col gap-1 text-sm">

templates/partials/brew_list.html

@@ -43,7 +43,12 @@
               <div class="text-xs text-stone-500 font-mono">{{ brew.ratio }}</div>
             </td>
             <td class="px-4 py-3 whitespace-nowrap">{{ brew.water_temp }}</td>
-            <td class="px-4 py-3 whitespace-nowrap">{{ brew.brewer_name }}</td>
+            <td class="px-4 py-3 whitespace-nowrap">
+              <div>{{ brew.brewer_name }}</div>
+              {% if let Some(fp_name) = brew.filter_paper_name %}
+              <div class="text-xs text-stone-500">{{ fp_name }}</div>
+              {% endif %}
+            </td>
             <td class="px-4 py-3 whitespace-nowrap text-stone-500">{{ brew.created_at }}</td>
             {% if is_authenticated %}
             <td class="px-4 py-3 text-right">
@@ -53,6 +58,9 @@
                 <input type="hidden" name="grinder_id" value="{{ brew.grinder_id }}" />
                 <input type="hidden" name="grind_setting" value="{{ brew.grind_setting_raw }}" />
                 <input type="hidden" name="brewer_id" value="{{ brew.brewer_id }}" />
+                {% if let Some(fp_id) = brew.filter_paper_id %}
+                <input type="hidden" name="filter_paper_id" value="{{ fp_id }}" />
+                {% endif %}
                 <input type="hidden" name="water_volume" value="{{ brew.water_volume_raw }}" />
                 <input type="hidden" name="water_temp" value="{{ brew.water_temp_raw }}" />
                 <button

templates/partials/timeline_month.html

@@ -63,6 +63,9 @@
         <input type="hidden" name="grinder_id" value="{{ brew.grinder_id }}" />
         <input type="hidden" name="grind_setting" value="{{ brew.grind_setting }}" />
         <input type="hidden" name="brewer_id" value="{{ brew.brewer_id }}" />
+        {% if let Some(fp_id) = brew.filter_paper_id %}
+        <input type="hidden" name="filter_paper_id" value="{{ fp_id }}" />
+        {% endif %}
         <input type="hidden" name="water_volume" value="{{ brew.water_volume }}" />
         <input type="hidden" name="water_temp" value="{{ brew.water_temp }}" />
         <button