feat(domain,application,infrastructure,backend,web-server,app-tauri,frontend): bibliothèque d'icônes projet personnalisées importées par l'utilisateur — #358 (QA verte)

domain: variante ProjectIconSet::Custom, métadonnées CustomProjectIconAsset (id opaque, media type png/jpeg/webp, byte_size, dimensions décodées, sha256, nom de fichier original sans chemin, created_at), CustomProjectIconContent et port CustomProjectIconAssetStore (list/read/exists/create/delete) avec CustomProjectIconStoreError dédiée.
application: use case project_icon_assets — import validé png/jpeg/webp avec rejet du contenu SVG, dimensionnement et digest sha256, bibliothèque partagée à l'instance indépendante de tout projet, suppression refusée tant que l'asset est référencé par un projet.
infrastructure: store fichier store/project_icon_asset.rs — index canonique + octets, création atomique sous extension validée.
backend/web-server: contrat HTTP /api/project-icon-assets (GET liste, POST import, GET lecture, GET /usage, DELETE) avec prévol OPTIONS et tests contrat incluant le rejet SVG.
app-tauri: commandes import/list/read/get_usage/delete_custom_project_icon_asset exposées au frontend.
frontend: port ProjectIconAssetGateway (list/import/delete/getUrl sans exposer de chemin filesystem), gateways http+mock avec tests, DI, section Icônes personnalisées du ProjectIconPicker (import fichier accept png/jpeg/webp, sélection role=option, suppression avec retrait de sélection, erreurs lisibles i18n FR/EN), tests projectIcons étendus.

QA verte: contrats HTTP et Tauri identiques, suites cargo et npm ciblées vertes.

crates/application/Cargo.toml

@@ -13,6 +13,7 @@ async-trait = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 sha2 = { workspace = true }
+hex = { workspace = true }
 subtle = { workspace = true }
 # Resolves the OpenCode cache dir (`~/.cache/opencode/models.json`) for the
 # dynamic provider catalogue (ticket #92 follow-up). See

crates/application/src/error.rs

@@ -41,6 +41,15 @@ pub enum AppError {
     #[error("concurrency conflict: {0}")]
     Conflict(String),
 
+    /// A custom icon cannot be removed while projects reference it.
+    #[error("custom icon {asset_id} is used by {used_by_project_count} project(s)")]
+    CustomIconInUse {
+        /// Stable asset id.
+        asset_id: String,
+        /// Current usage count.
+        used_by_project_count: u64,
+    },
+
     /// A filesystem operation failed.
     #[error("filesystem error: {0}")]
     FileSystem(String),
@@ -161,6 +170,7 @@ impl AppError {
             Self::Invalid(_) => "INVALID",
             Self::AmbiguousSkillName { .. } => "ambiguousSkillName",
             Self::Conflict(_) => "CONFLICT",
+            Self::CustomIconInUse { .. } => "CUSTOM_ICON_IN_USE",
             Self::FileSystem(_) => "FILESYSTEM",
             Self::Store(_) => "STORE",
             Self::Process(_) => "PROCESS",

crates/application/src/lib.rs

@@ -33,6 +33,7 @@ pub mod orchestrator;
 pub mod permission;
 pub mod plugin;
 pub mod project;
+pub mod project_icon_assets;
 pub mod project_plugin;
 pub mod remote;
 pub mod scheduled_task;
@@ -220,6 +221,12 @@ pub use project::{
     RetryOpenProjectRestore, SaveOpenProjectRestoreOrder, UpdateProjectContext,
     UpdateProjectContextInput, PROJECT_CONTEXT_FILE,
 };
+pub use project_icon_assets::{
+    CustomProjectIconAssetView, CustomProjectIconContentView, CustomProjectIconUsage,
+    DeleteCustomProjectIconAsset, GetCustomProjectIconAssetUsage, ImportCustomProjectIconAsset,
+    ListCustomProjectIconAssets, ReadCustomProjectIconAsset, CUSTOM_PROJECT_ICON_MAX_BYTES,
+    CUSTOM_PROJECT_ICON_MAX_DIMENSION,
+};
 pub use project_plugin::{
     plugin_skill_ref, plugin_tool_ref, AssignmentMutation, ListProjectPluginSettings,
     MutateAgentPluginSkill, MutateAgentPluginTool, ProjectPluginResolver,

crates/application/src/project_icon_assets.rs

@@ -0,0 +1,502 @@
+//! Use cases for the instance-local custom project icon library.
+
+use crate::AppError;
+use domain::{
+    Clock, CustomProjectIconAsset, CustomProjectIconAssetStore, CustomProjectIconContent,
+    CustomProjectIconStoreError, IdGenerator, ProjectIconSet, ProjectSettingsStore, ProjectStore,
+};
+use sha2::{Digest, Sha256};
+use std::sync::Arc;
+
+/// Maximum accepted encoded image size (2 MiB).
+pub const CUSTOM_PROJECT_ICON_MAX_BYTES: usize = 2 * 1024 * 1024;
+/// Maximum accepted width or height.
+pub const CUSTOM_PROJECT_ICON_MAX_DIMENSION: u32 = 4096;
+
+/// Asset metadata enriched with its current project usage count.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CustomProjectIconAssetView {
+    /// Persisted metadata.
+    pub asset: CustomProjectIconAsset,
+    /// Number of registered projects currently referencing the asset.
+    pub used_by_project_count: u64,
+}
+
+/// Asset bytes enriched with usage metadata.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CustomProjectIconContentView {
+    /// Metadata and usage.
+    pub metadata: CustomProjectIconAssetView,
+    /// Exact validated raster bytes.
+    pub bytes: Vec<u8>,
+}
+
+/// Usage result returned before deletion or for user feedback.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CustomProjectIconUsage {
+    /// Stable asset id.
+    pub asset_id: String,
+    /// Number of registered projects referencing it.
+    pub used_by_project_count: u64,
+}
+
+/// Imports one validated raster into the shared library.
+pub struct ImportCustomProjectIconAsset {
+    store: Arc<dyn CustomProjectIconAssetStore>,
+    ids: Arc<dyn IdGenerator>,
+    clock: Arc<dyn Clock>,
+}
+
+impl ImportCustomProjectIconAsset {
+    /// Builds the use case.
+    #[must_use]
+    pub fn new(
+        store: Arc<dyn CustomProjectIconAssetStore>,
+        ids: Arc<dyn IdGenerator>,
+        clock: Arc<dyn Clock>,
+    ) -> Self {
+        Self { store, ids, clock }
+    }
+
+    /// Validates real content, declared MIME and filename extension before persisting.
+    pub async fn execute(
+        &self,
+        original_filename: String,
+        declared_media_type: String,
+        bytes: Vec<u8>,
+    ) -> Result<CustomProjectIconAssetView, AppError> {
+        if bytes.is_empty() || bytes.len() > CUSTOM_PROJECT_ICON_MAX_BYTES {
+            return Err(AppError::Invalid(format!(
+                "custom project icon must contain 1..={CUSTOM_PROJECT_ICON_MAX_BYTES} bytes"
+            )));
+        }
+        let filename = safe_basename(&original_filename)?;
+        let detected = detect_raster(&bytes)?;
+        if declared_media_type.trim().to_ascii_lowercase() != detected.media_type {
+            return Err(AppError::Invalid(format!(
+                "declared media type does not match {} content",
+                detected.media_type
+            )));
+        }
+        let filename_extension = filename
+            .rsplit_once('.')
+            .map(|(_, extension)| extension.to_ascii_lowercase())
+            .ok_or_else(|| {
+                AppError::Invalid("custom project icon filename needs an extension".to_owned())
+            })?;
+        if !detected.extensions.contains(&filename_extension.as_str()) {
+            return Err(AppError::Invalid(
+                "custom project icon filename extension does not match its content".to_owned(),
+            ));
+        }
+        if detected.width == 0
+            || detected.height == 0
+            || detected.width > CUSTOM_PROJECT_ICON_MAX_DIMENSION
+            || detected.height > CUSTOM_PROJECT_ICON_MAX_DIMENSION
+        {
+            return Err(AppError::Invalid(format!(
+                "custom project icon dimensions must be 1..={CUSTOM_PROJECT_ICON_MAX_DIMENSION} pixels"
+            )));
+        }
+
+        let asset = CustomProjectIconAsset {
+            id: self.ids.new_uuid().simple().to_string(),
+            media_type: detected.media_type.to_owned(),
+            byte_size: bytes.len() as u64,
+            width: detected.width,
+            height: detected.height,
+            sha256: hex::encode(Sha256::digest(&bytes)),
+            original_filename: filename,
+            created_at: self.clock.now_millis(),
+        };
+        self.store
+            .create(&asset, detected.extension, &bytes)
+            .await?;
+        Ok(CustomProjectIconAssetView {
+            asset,
+            used_by_project_count: 0,
+        })
+    }
+}
+
+/// Lists all custom icons with live usage counts.
+pub struct ListCustomProjectIconAssets {
+    store: Arc<dyn CustomProjectIconAssetStore>,
+    projects: Arc<dyn ProjectStore>,
+    settings: Arc<dyn ProjectSettingsStore>,
+}
+
+impl ListCustomProjectIconAssets {
+    /// Builds the use case.
+    #[must_use]
+    pub fn new(
+        store: Arc<dyn CustomProjectIconAssetStore>,
+        projects: Arc<dyn ProjectStore>,
+        settings: Arc<dyn ProjectSettingsStore>,
+    ) -> Self {
+        Self {
+            store,
+            projects,
+            settings,
+        }
+    }
+    /// Lists metadata in stable order.
+    pub async fn execute(&self) -> Result<Vec<CustomProjectIconAssetView>, AppError> {
+        let assets = self.store.list().await?;
+        let mut output = Vec::with_capacity(assets.len());
+        for asset in assets {
+            let count = usage_count(&asset.id, &self.projects, &self.settings).await?;
+            output.push(CustomProjectIconAssetView {
+                asset,
+                used_by_project_count: count,
+            });
+        }
+        Ok(output)
+    }
+}
+
+/// Reads one custom icon and its current usage.
+pub struct ReadCustomProjectIconAsset {
+    store: Arc<dyn CustomProjectIconAssetStore>,
+    projects: Arc<dyn ProjectStore>,
+    settings: Arc<dyn ProjectSettingsStore>,
+}
+
+impl ReadCustomProjectIconAsset {
+    /// Builds the use case.
+    #[must_use]
+    pub fn new(
+        store: Arc<dyn CustomProjectIconAssetStore>,
+        projects: Arc<dyn ProjectStore>,
+        settings: Arc<dyn ProjectSettingsStore>,
+    ) -> Self {
+        Self {
+            store,
+            projects,
+            settings,
+        }
+    }
+    /// Reads exact bytes after validating the opaque id shape.
+    pub async fn execute(&self, asset_id: &str) -> Result<CustomProjectIconContentView, AppError> {
+        validate_asset_id(asset_id)?;
+        let CustomProjectIconContent { asset, bytes } = self.store.read(asset_id).await?;
+        let count = usage_count(asset_id, &self.projects, &self.settings).await?;
+        Ok(CustomProjectIconContentView {
+            metadata: CustomProjectIconAssetView {
+                asset,
+                used_by_project_count: count,
+            },
+            bytes,
+        })
+    }
+}
+
+/// Gets live project usage for one existing asset.
+pub struct GetCustomProjectIconAssetUsage {
+    store: Arc<dyn CustomProjectIconAssetStore>,
+    projects: Arc<dyn ProjectStore>,
+    settings: Arc<dyn ProjectSettingsStore>,
+}
+
+impl GetCustomProjectIconAssetUsage {
+    /// Builds the use case.
+    #[must_use]
+    pub fn new(
+        store: Arc<dyn CustomProjectIconAssetStore>,
+        projects: Arc<dyn ProjectStore>,
+        settings: Arc<dyn ProjectSettingsStore>,
+    ) -> Self {
+        Self {
+            store,
+            projects,
+            settings,
+        }
+    }
+    /// Returns usage, rejecting unknown ids.
+    pub async fn execute(&self, asset_id: &str) -> Result<CustomProjectIconUsage, AppError> {
+        validate_asset_id(asset_id)?;
+        if !self.store.exists(asset_id).await? {
+            return Err(AppError::NotFound(format!(
+                "custom project icon asset {asset_id}"
+            )));
+        }
+        Ok(CustomProjectIconUsage {
+            asset_id: asset_id.to_owned(),
+            used_by_project_count: usage_count(asset_id, &self.projects, &self.settings).await?,
+        })
+    }
+}
+
+/// Deletes one asset only when no registered project references it.
+pub struct DeleteCustomProjectIconAsset {
+    store: Arc<dyn CustomProjectIconAssetStore>,
+    projects: Arc<dyn ProjectStore>,
+    settings: Arc<dyn ProjectSettingsStore>,
+}
+
+impl DeleteCustomProjectIconAsset {
+    /// Builds the use case.
+    #[must_use]
+    pub fn new(
+        store: Arc<dyn CustomProjectIconAssetStore>,
+        projects: Arc<dyn ProjectStore>,
+        settings: Arc<dyn ProjectSettingsStore>,
+    ) -> Self {
+        Self {
+            store,
+            projects,
+            settings,
+        }
+    }
+    /// Deletes an unused asset and returns its former usage.
+    pub async fn execute(&self, asset_id: &str) -> Result<CustomProjectIconUsage, AppError> {
+        validate_asset_id(asset_id)?;
+        if !self.store.exists(asset_id).await? {
+            return Err(AppError::NotFound(format!(
+                "custom project icon asset {asset_id}"
+            )));
+        }
+        let used_by_project_count = usage_count(asset_id, &self.projects, &self.settings).await?;
+        if used_by_project_count > 0 {
+            return Err(AppError::CustomIconInUse {
+                asset_id: asset_id.to_owned(),
+                used_by_project_count,
+            });
+        }
+        self.store.delete(asset_id).await?;
+        Ok(CustomProjectIconUsage {
+            asset_id: asset_id.to_owned(),
+            used_by_project_count,
+        })
+    }
+}
+
+pub(crate) fn validate_asset_id(asset_id: &str) -> Result<(), AppError> {
+    let valid = !asset_id.is_empty()
+        && asset_id.len() <= 64
+        && asset_id
+            .bytes()
+            .all(|byte| byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_'));
+    valid
+        .then_some(())
+        .ok_or_else(|| AppError::Invalid("invalid custom project icon asset id".to_owned()))
+}
+
+async fn usage_count(
+    asset_id: &str,
+    projects: &Arc<dyn ProjectStore>,
+    settings: &Arc<dyn ProjectSettingsStore>,
+) -> Result<u64, AppError> {
+    let mut count = 0_u64;
+    for project in projects.list_projects().await? {
+        let project_settings = settings.load(&project.root).await?;
+        if project_settings
+            .icon
+            .as_ref()
+            .is_some_and(|icon| icon.set() == ProjectIconSet::Custom && icon.name() == asset_id)
+        {
+            count += 1;
+        }
+    }
+    Ok(count)
+}
+
+fn safe_basename(raw: &str) -> Result<String, AppError> {
+    let name = raw.rsplit(['/', '\\']).next().unwrap_or("").trim();
+    if name.is_empty() || name.len() > 255 || name.chars().any(char::is_control) {
+        return Err(AppError::Invalid(
+            "invalid custom project icon filename".to_owned(),
+        ));
+    }
+    Ok(name.to_owned())
+}
+
+struct DetectedRaster {
+    media_type: &'static str,
+    extension: &'static str,
+    extensions: &'static [&'static str],
+    width: u32,
+    height: u32,
+}
+
+fn detect_raster(bytes: &[u8]) -> Result<DetectedRaster, AppError> {
+    if bytes.len() >= 45
+        && bytes.starts_with(b"\x89PNG\r\n\x1a\n")
+        && bytes[8..12] == 13_u32.to_be_bytes()
+        && &bytes[12..16] == b"IHDR"
+        && valid_png_chunks(bytes)
+    {
+        return Ok(DetectedRaster {
+            media_type: "image/png",
+            extension: "png",
+            extensions: &["png"],
+            width: u32::from_be_bytes(bytes[16..20].try_into().unwrap()),
+            height: u32::from_be_bytes(bytes[20..24].try_into().unwrap()),
+        });
+    }
+    if bytes.len() >= 30
+        && bytes.starts_with(b"RIFF")
+        && &bytes[8..12] == b"WEBP"
+        && usize::try_from(u32::from_le_bytes(bytes[4..8].try_into().unwrap())).ok()
+            == Some(bytes.len() - 8)
+    {
+        if &bytes[12..16] == b"VP8X" {
+            let width = 1 + u32::from_le_bytes([bytes[24], bytes[25], bytes[26], 0]);
+            let height = 1 + u32::from_le_bytes([bytes[27], bytes[28], bytes[29], 0]);
+            return Ok(DetectedRaster {
+                media_type: "image/webp",
+                extension: "webp",
+                extensions: &["webp"],
+                width,
+                height,
+            });
+        }
+        if &bytes[12..16] == b"VP8L" && bytes.len() >= 25 && bytes[20] == 0x2f {
+            let bits = u32::from_le_bytes(bytes[21..25].try_into().unwrap());
+            return Ok(DetectedRaster {
+                media_type: "image/webp",
+                extension: "webp",
+                extensions: &["webp"],
+                width: (bits & 0x3fff) + 1,
+                height: ((bits >> 14) & 0x3fff) + 1,
+            });
+        }
+        if &bytes[12..16] == b"VP8 " && bytes.len() >= 30 && bytes[23..26] == [0x9d, 0x01, 0x2a] {
+            let width = u16::from_le_bytes(bytes[26..28].try_into().unwrap()) & 0x3fff;
+            let height = u16::from_le_bytes(bytes[28..30].try_into().unwrap()) & 0x3fff;
+            return Ok(DetectedRaster {
+                media_type: "image/webp",
+                extension: "webp",
+                extensions: &["webp"],
+                width: u32::from(width),
+                height: u32::from(height),
+            });
+        }
+        return Err(AppError::Invalid(
+            "unsupported or malformed WebP image".to_owned(),
+        ));
+    }
+    if bytes.starts_with(&[0xff, 0xd8]) && bytes.ends_with(&[0xff, 0xd9]) {
+        let (width, height) = jpeg_dimensions(bytes)?;
+        return Ok(DetectedRaster {
+            media_type: "image/jpeg",
+            extension: "jpg",
+            extensions: &["jpg", "jpeg"],
+            width,
+            height,
+        });
+    }
+    Err(AppError::Invalid(
+        "custom project icon must be PNG, JPEG or WebP; SVG and GIF are not supported".to_owned(),
+    ))
+}
+
+fn valid_png_chunks(bytes: &[u8]) -> bool {
+    let mut cursor = 8_usize;
+    while cursor + 12 <= bytes.len() {
+        let length = u32::from_be_bytes(bytes[cursor..cursor + 4].try_into().unwrap()) as usize;
+        let Some(end) = cursor
+            .checked_add(12)
+            .and_then(|value| value.checked_add(length))
+        else {
+            return false;
+        };
+        if end > bytes.len() {
+            return false;
+        }
+        if &bytes[cursor + 4..cursor + 8] == b"IEND" {
+            return length == 0 && end == bytes.len();
+        }
+        cursor = end;
+    }
+    false
+}
+
+fn jpeg_dimensions(bytes: &[u8]) -> Result<(u32, u32), AppError> {
+    let mut cursor = 2;
+    while cursor + 4 <= bytes.len() {
+        while cursor < bytes.len() && bytes[cursor] != 0xff {
+            cursor += 1;
+        }
+        while cursor < bytes.len() && bytes[cursor] == 0xff {
+            cursor += 1;
+        }
+        if cursor >= bytes.len() {
+            break;
+        }
+        let marker = bytes[cursor];
+        cursor += 1;
+        if marker == 0xd9 || marker == 0xda {
+            break;
+        }
+        if marker == 0x01 || (0xd0..=0xd7).contains(&marker) {
+            continue;
+        }
+        if cursor + 2 > bytes.len() {
+            break;
+        }
+        let length = usize::from(u16::from_be_bytes(
+            bytes[cursor..cursor + 2].try_into().unwrap(),
+        ));
+        if length < 2 || cursor + length > bytes.len() {
+            break;
+        }
+        if matches!(marker, 0xc0..=0xc3 | 0xc5..=0xc7 | 0xc9..=0xcb | 0xcd..=0xcf) && length >= 7 {
+            let height = u32::from(u16::from_be_bytes(
+                bytes[cursor + 3..cursor + 5].try_into().unwrap(),
+            ));
+            let width = u32::from(u16::from_be_bytes(
+                bytes[cursor + 5..cursor + 7].try_into().unwrap(),
+            ));
+            return Ok((width, height));
+        }
+        cursor += length;
+    }
+    Err(AppError::Invalid("malformed JPEG image".to_owned()))
+}
+
+impl From<CustomProjectIconStoreError> for AppError {
+    fn from(error: CustomProjectIconStoreError) -> Self {
+        match error {
+            CustomProjectIconStoreError::NotFound => {
+                Self::NotFound("custom project icon asset".to_owned())
+            }
+            CustomProjectIconStoreError::Format(message) => Self::Store(message),
+            CustomProjectIconStoreError::Io(message) => Self::FileSystem(message),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn detects_png_dimensions_and_rejects_svg() {
+        let mut png = b"\x89PNG\r\n\x1a\n\0\0\0\rIHDR".to_vec();
+        png.extend_from_slice(&32_u32.to_be_bytes());
+        png.extend_from_slice(&48_u32.to_be_bytes());
+        png.extend_from_slice(&[8, 6, 0, 0, 0]);
+        png.extend_from_slice(&[0, 0, 0, 0]);
+        png.extend_from_slice(&[0, 0, 0, 0]);
+        png.extend_from_slice(b"IEND");
+        png.extend_from_slice(&[0, 0, 0, 0]);
+        assert_eq!(
+            (
+                detect_raster(&png).unwrap().width,
+                detect_raster(&png).unwrap().height
+            ),
+            (32, 48)
+        );
+        assert!(detect_raster(b"<svg></svg>").is_err());
+    }
+
+    #[test]
+    fn confines_filename_to_basename() {
+        assert_eq!(safe_basename("/tmp/user/icon.png").unwrap(), "icon.png");
+        assert_eq!(
+            safe_basename(r"C:\\Users\\me\\icon.webp").unwrap(),
+            "icon.webp"
+        );
+    }
+}

crates/application/src/settings.rs

@@ -2,8 +2,8 @@
 
 use crate::AppError;
 use domain::{
-    IdeaUserSettings, Project, ProjectIconRef, ProjectSettings, ProjectSettingsStore, ThemeColor,
-    UserSettingsStore,
+    CustomProjectIconAssetStore, IdeaUserSettings, Project, ProjectIconRef, ProjectIconSet,
+    ProjectSettings, ProjectSettingsStore, ThemeColor, UserSettingsStore,
 };
 use std::sync::Arc;
 
@@ -56,12 +56,16 @@ impl ReadProjectSettings {
 /// Updates the settings owned by one project.
 pub struct UpdateProjectSettings {
     store: Arc<dyn ProjectSettingsStore>,
+    icon_assets: Arc<dyn CustomProjectIconAssetStore>,
 }
 impl UpdateProjectSettings {
     /// Builds the use case.
     #[must_use]
-    pub fn new(store: Arc<dyn ProjectSettingsStore>) -> Self {
-        Self { store }
+    pub fn new(
+        store: Arc<dyn ProjectSettingsStore>,
+        icon_assets: Arc<dyn CustomProjectIconAssetStore>,
+    ) -> Self {
+        Self { store, icon_assets }
     }
     /// Applies the supplied fields and returns the accepted project settings.
     ///
@@ -73,6 +77,17 @@ impl UpdateProjectSettings {
         theme_color: Option<Option<ThemeColor>>,
         icon: Option<Option<ProjectIconRef>>,
     ) -> Result<ProjectSettings, AppError> {
+        if let Some(Some(icon)) = &icon {
+            if icon.set() == ProjectIconSet::Custom {
+                crate::project_icon_assets::validate_asset_id(icon.name())?;
+                if !self.icon_assets.exists(icon.name()).await? {
+                    return Err(AppError::Invalid(format!(
+                        "custom project icon asset does not exist: {}",
+                        icon.name()
+                    )));
+                }
+            }
+        }
         let mut settings = self.store.load(&project.root).await?;
         let mut changed = false;
         if let Some(theme_color) = theme_color {
@@ -94,10 +109,41 @@ impl UpdateProjectSettings {
 mod tests {
     use super::*;
     use async_trait::async_trait;
-    use domain::{ProjectIconSet, ProjectPath, RemoteRef, StoreError};
+    use domain::{
+        CustomProjectIconAsset, CustomProjectIconContent, CustomProjectIconStoreError,
+        ProjectIconSet, ProjectPath, RemoteRef, StoreError,
+    };
     use std::sync::Mutex;
 
     struct MemoryProjectSettings(Mutex<ProjectSettings>);
+    struct MemoryIconAssets;
+
+    #[async_trait]
+    impl CustomProjectIconAssetStore for MemoryIconAssets {
+        async fn list(&self) -> Result<Vec<CustomProjectIconAsset>, CustomProjectIconStoreError> {
+            Ok(Vec::new())
+        }
+        async fn read(
+            &self,
+            _asset_id: &str,
+        ) -> Result<CustomProjectIconContent, CustomProjectIconStoreError> {
+            Err(CustomProjectIconStoreError::NotFound)
+        }
+        async fn exists(&self, asset_id: &str) -> Result<bool, CustomProjectIconStoreError> {
+            Ok(asset_id == "known")
+        }
+        async fn create(
+            &self,
+            _asset: &CustomProjectIconAsset,
+            _extension: &str,
+            _bytes: &[u8],
+        ) -> Result<(), CustomProjectIconStoreError> {
+            Ok(())
+        }
+        async fn delete(&self, _asset_id: &str) -> Result<(), CustomProjectIconStoreError> {
+            Ok(())
+        }
+    }
 
     #[async_trait]
     impl ProjectSettingsStore for MemoryProjectSettings {
@@ -132,7 +178,7 @@ mod tests {
             theme_color: Some(ThemeColor::new("#123456").unwrap()),
             icon: Some(ProjectIconRef::new(ProjectIconSet::Devicon, "rust").unwrap()),
         })));
-        let update = UpdateProjectSettings::new(store);
+        let update = UpdateProjectSettings::new(store, Arc::new(MemoryIconAssets));
         let project = project();
 
         let icon = ProjectIconRef::new(ProjectIconSet::Lucide, "star").unwrap();
@@ -170,4 +216,18 @@ mod tests {
             Some("#ABCDEF")
         );
     }
+
+    #[tokio::test]
+    async fn project_settings_rejects_missing_custom_icon() {
+        let store = Arc::new(MemoryProjectSettings(
+            Mutex::new(ProjectSettings::default()),
+        ));
+        let update = UpdateProjectSettings::new(store, Arc::new(MemoryIconAssets));
+        let icon = ProjectIconRef::new(ProjectIconSet::Custom, "missing").unwrap();
+        let error = update
+            .execute(&project(), None, Some(Some(icon)))
+            .await
+            .unwrap_err();
+        assert_eq!(error.code(), "INVALID");
+    }
 }