diff --git a/src/application/routes/account.rs b/src/application/routes/account.rs
index d7e3010..5afa2b7 100644
--- a/src/application/routes/account.rs
+++ b/src/application/routes/account.rs
@@ -6,6 +6,7 @@ use axum::response::{IntoResponse, Redirect, Response};
 use chrono::{DateTime, Utc};
 use serde::Serialize;
 use tower_cookies::Cookies;
+use tracing::{error, info, warn};
 
 use crate::application::auth::AuthenticatedUser;
 use crate::application::routes::render_html;
@@ -98,7 +99,10 @@ pub(crate) async fn account_page(
         .passkey_repo
         .list_by_user(auth_user.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
+        .map_err(|err| {
+            error!(error = %err, "failed to list passkeys for account page");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?
         .into_iter()
         .map(|p| PasskeyView {
             id: i64::from(p.id),
@@ -112,7 +116,10 @@ pub(crate) async fn account_page(
         .token_repo
         .list_by_user(auth_user.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
+        .map_err(|err| {
+            error!(error = %err, "failed to list tokens for account page");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?
         .into_iter()
         .filter(crate::domain::tokens::Token::is_active)
         .map(|t| TokenView {
@@ -123,17 +130,18 @@ pub(crate) async fn account_page(
         })
         .collect();
 
-    let ai_usage = state
-        .ai_usage_repo
-        .summary_for_user(auth_user.id)
-        .await
-        .ok()
-        .filter(|s| s.total_calls > 0)
-        .map(|s| AiUsageView {
-            total_calls: s.total_calls,
-            total_tokens: format_number(s.total_tokens),
-            total_cost: format_cost(s.total_cost),
-        });
+    let ai_usage = match state.ai_usage_repo.summary_for_user(auth_user.id).await {
+        Ok(summary) => Some(summary),
+        Err(err) => {
+            warn!(error = %err, "failed to load AI usage summary");
+            None
+        }
+    };
+    let ai_usage = ai_usage.filter(|s| s.total_calls > 0).map(|s| AiUsageView {
+        total_calls: s.total_calls,
+        total_tokens: format_number(s.total_tokens),
+        total_cost: format_cost(s.total_cost),
+    });
 
     let template = AccountTemplate {
         nav_active: "account",
@@ -165,7 +173,10 @@ pub(crate) async fn list_passkeys(
         .passkey_repo
         .list_by_user(auth_user.0.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        .map_err(|err| {
+            error!(error = %err, "failed to list passkeys");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
 
     let responses: Vec<PasskeyResponse> = passkeys
         .into_iter()
@@ -186,11 +197,10 @@ pub(crate) async fn delete_passkey(
     Path(passkey_id): Path<PasskeyCredentialId>,
 ) -> Result<StatusCode, StatusCode> {
     // Verify the passkey belongs to the user
-    let passkey = state
-        .passkey_repo
-        .get(passkey_id)
-        .await
-        .map_err(|_| StatusCode::NOT_FOUND)?;
+    let passkey = state.passkey_repo.get(passkey_id).await.map_err(|err| {
+        error!(error = %err, %passkey_id, "failed to get passkey for deletion");
+        StatusCode::NOT_FOUND
+    })?;
 
     if passkey.user_id != auth_user.0.id {
         return Err(StatusCode::FORBIDDEN);
@@ -201,17 +211,21 @@ pub(crate) async fn delete_passkey(
         .passkey_repo
         .list_by_user(auth_user.0.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        .map_err(|err| {
+            error!(error = %err, "failed to list passkeys for deletion check");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
 
     if all_passkeys.len() <= 1 {
         return Err(StatusCode::CONFLICT);
     }
 
-    state
-        .passkey_repo
-        .delete(passkey_id)
-        .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    state.passkey_repo.delete(passkey_id).await.map_err(|err| {
+        error!(error = %err, %passkey_id, "failed to delete passkey");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
+
+    info!(%passkey_id, user_id = %auth_user.0.id, "passkey deleted");
 
     Ok(StatusCode::NO_CONTENT)
 }
@@ -226,15 +240,27 @@ async fn extract_user_from_session(
     let session_token = cookie.value();
     let session_token_hash = crate::infrastructure::auth::hash_token(session_token);
 
-    let session = state
+    let session = match state
         .session_repo
         .get_by_token_hash(&session_token_hash)
         .await
-        .ok()?;
+    {
+        Ok(s) => s,
+        Err(err) => {
+            warn!(error = %err, "session lookup failed on account page");
+            return None;
+        }
+    };
 
     if session.is_expired() {
         return None;
     }
 
-    state.user_repo.get(session.user_id).await.ok()
+    match state.user_repo.get(session.user_id).await {
+        Ok(user) => Some(user),
+        Err(err) => {
+            warn!(error = %err, user_id = %session.user_id, "user lookup failed for valid session");
+            None
+        }
+    }
 }
diff --git a/src/application/routes/auth.rs b/src/application/routes/auth.rs
index ccc2a0f..ea91a2a 100644
--- a/src/application/routes/auth.rs
+++ b/src/application/routes/auth.rs
@@ -4,6 +4,7 @@ use axum::http::StatusCode;
 use axum::response::{IntoResponse, Redirect, Response};
 use serde::Deserialize;
 use tower_cookies::{Cookie, Cookies};
+use tracing::{info, warn};
 
 use crate::application::routes::render_html;
 use crate::application::server::AppState;
@@ -55,11 +56,13 @@ pub(crate) async fn logout(State(state): State<AppState>, cookies: Cookies) -> R
             .session_repo
             .get_by_token_hash(&session_token_hash)
             .await
+            && let Err(err) = state.session_repo.delete(session.id).await
         {
-            let _ = state.session_repo.delete(session.id).await;
+            warn!(error = %err, session_id = %session.id, "failed to delete session on logout");
         }
     }
 
+    info!("user logged out");
     cookies.remove(Cookie::from(SESSION_COOKIE_NAME));
     Redirect::to("/")
 }
@@ -79,6 +82,9 @@ pub async fn is_authenticated(state: &AppState, cookies: &Cookies) -> bool {
         .await
     {
         Ok(session) => !session.is_expired(),
-        Err(_) => false,
+        Err(err) => {
+            warn!(error = %err, "session lookup failed during auth check");
+            false
+        }
     }
 }
diff --git a/src/application/routes/tokens.rs b/src/application/routes/tokens.rs
index 1ca14da..5d62b30 100644
--- a/src/application/routes/tokens.rs
+++ b/src/application/routes/tokens.rs
@@ -3,6 +3,7 @@ use axum::extract::{Path, State};
 use axum::http::StatusCode;
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
+use tracing::{error, info};
 
 use crate::application::auth::AuthenticatedUser;
 use crate::application::server::AppState;
@@ -51,16 +52,20 @@ pub async fn create_token(
     auth_user: AuthenticatedUser,
     Json(payload): Json<CreateTokenRequest>,
 ) -> Result<Json<CreateTokenResponse>, StatusCode> {
-    let token_value = generate_token().map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let token_value = generate_token().map_err(|err| {
+        error!(error = %err, "failed to generate token");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
     let token_hash_value = hash_token(&token_value);
 
     let new_token = NewToken::new(auth_user.0.id, token_hash_value, payload.name.clone());
 
-    let stored_token = state
-        .token_repo
-        .insert(new_token)
-        .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let stored_token = state.token_repo.insert(new_token).await.map_err(|err| {
+        error!(error = %err, "failed to store token");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
+
+    info!(token_id = %stored_token.id, token_name = %stored_token.name, user_id = %auth_user.0.id, "API token created");
 
     Ok(Json(CreateTokenResponse {
         id: stored_token.id,
@@ -78,7 +83,10 @@ pub async fn list_tokens(
         .token_repo
         .list_by_user(auth_user.0.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        .map_err(|err| {
+            error!(error = %err, "failed to list tokens");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
 
     let token_responses: Vec<TokenResponse> = tokens.into_iter().map(TokenResponse::from).collect();
 
@@ -92,11 +100,10 @@ pub async fn revoke_token(
     Path(token_id): Path<TokenId>,
 ) -> Result<Json<TokenResponse>, StatusCode> {
     // Get the token to ensure it exists and belongs to the user
-    let token = state
-        .token_repo
-        .get(token_id)
-        .await
-        .map_err(|_| StatusCode::NOT_FOUND)?;
+    let token = state.token_repo.get(token_id).await.map_err(|err| {
+        error!(error = %err, %token_id, "failed to get token for revocation");
+        StatusCode::NOT_FOUND
+    })?;
 
     // Ensure the token belongs to the authenticated user
     if token.user_id != auth_user.0.id {
@@ -104,11 +111,12 @@ pub async fn revoke_token(
     }
 
     // Revoke the token
-    let revoked_token = state
-        .token_repo
-        .revoke(token_id)
-        .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let revoked_token = state.token_repo.revoke(token_id).await.map_err(|err| {
+        error!(error = %err, %token_id, "failed to revoke token");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
+
+    info!(%token_id, user_id = %auth_user.0.id, "API token revoked");
 
     Ok(Json(TokenResponse::from(revoked_token)))
 }
diff --git a/src/application/routes/webauthn.rs b/src/application/routes/webauthn.rs
index b5ccde5..e0a6f72 100644
--- a/src/application/routes/webauthn.rs
+++ b/src/application/routes/webauthn.rs
@@ -138,7 +138,10 @@ pub(crate) async fn register_start(
         .registration_token_repo
         .get_by_token_hash(&token_hash)
         .await
-        .map_err(|_| StatusCode::UNAUTHORIZED)?;
+        .map_err(|err| {
+            warn!(error = %err, "registration token lookup failed");
+            StatusCode::UNAUTHORIZED
+        })?;
 
     if !reg_token.is_valid() {
         return Err(StatusCode::GONE);
@@ -153,14 +156,19 @@ pub(crate) async fn register_start(
     })?;
 
     // Mark registration token as used
-    let _ = state
+    if let Err(err) = state
         .registration_token_repo
         .mark_used(reg_token.id, user.id)
-        .await;
+        .await
+    {
+        warn!(error = %err, token_id = %reg_token.id, "failed to mark registration token as used");
+    }
 
     // Start passkey registration ceremony
-    let webauthn_uuid =
-        Uuid::parse_str(&user_uuid).map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let webauthn_uuid = Uuid::parse_str(&user_uuid).map_err(|err| {
+        error!(error = %err, "failed to parse user UUID");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
     let exclude_credentials = Vec::new();
 
     let (ccr, reg_state) = state
@@ -214,8 +222,10 @@ pub(crate) async fn register_finish(
         })?;
 
     // Store the credential
-    let credential_json =
-        serde_json::to_string(&passkey).map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let credential_json = serde_json::to_string(&passkey).map_err(|err| {
+        error!(error = %err, "failed to serialize passkey credential");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
     let new_credential = NewPasskeyCredential::new(user_id, credential_json, payload.passkey_name);
     state
         .passkey_repo
@@ -242,11 +252,10 @@ pub(crate) async fn auth_start(
     Query(query): Query<AuthStartQuery>,
 ) -> Result<Json<AuthStartResponse>, StatusCode> {
     // Load all passkey credentials from all users
-    let users = state
-        .user_repo
-        .list_all()
-        .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let users = state.user_repo.list_all().await.map_err(|err| {
+        error!(error = %err, "failed to list users for auth start");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
 
     let mut all_passkeys: Vec<Passkey> = Vec::new();
     for user in &users {
@@ -254,7 +263,10 @@ pub(crate) async fn auth_start(
             .passkey_repo
             .list_by_user(user.id)
             .await
-            .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+            .map_err(|err| {
+                error!(error = %err, user_id = %user.id, "failed to list passkeys for user");
+                StatusCode::INTERNAL_SERVER_ERROR
+            })?;
 
         for cred in credentials {
             let passkey: Passkey = serde_json::from_str(&cred.credential_json).map_err(|err| {
@@ -300,6 +312,7 @@ pub(crate) async fn auth_start(
 
 // --- Authentication finish ---
 
+#[allow(clippy::too_many_lines)]
 #[tracing::instrument(skip(state, cookies, payload))]
 pub(crate) async fn auth_finish(
     State(state): State<AppState>,
@@ -324,11 +337,10 @@ pub(crate) async fn auth_finish(
 
     // Find the user who owns this credential
     let credential_id = auth_result.cred_id();
-    let users = state
-        .user_repo
-        .list_all()
-        .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let users = state.user_repo.list_all().await.map_err(|err| {
+        error!(error = %err, "failed to list users for credential lookup");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
 
     let mut found_user_id = None;
     let mut found_cred_id = None;
@@ -339,11 +351,17 @@ pub(crate) async fn auth_finish(
             .passkey_repo
             .list_by_user(user.id)
             .await
-            .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+            .map_err(|err| {
+                error!(error = %err, user_id = %user.id, "failed to list passkeys for user");
+                StatusCode::INTERNAL_SERVER_ERROR
+            })?;
 
         for cred in &credentials {
             let passkey: Passkey = serde_json::from_str(&cred.credential_json)
-                .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+                .map_err(|err| {
+                    error!(error = %err, credential_id = %cred.id, "failed to deserialize passkey credential");
+                    StatusCode::INTERNAL_SERVER_ERROR
+                })?;
             if passkey.cred_id() == credential_id {
                 found_user_id = Some(user.id);
                 found_cred_id = Some(cred.id);
@@ -361,31 +379,45 @@ pub(crate) async fn auth_finish(
         && let Some(mut passkey) = found_passkey
     {
         passkey.update_credential(&auth_result);
-        if let Ok(updated_json) = serde_json::to_string(&passkey) {
-            let _ = state
-                .passkey_repo
-                .update_credential_json(cred_db_id, &updated_json)
-                .await;
+        match serde_json::to_string(&passkey) {
+            Ok(updated_json) => {
+                if let Err(err) = state
+                    .passkey_repo
+                    .update_credential_json(cred_db_id, &updated_json)
+                    .await
+                {
+                    warn!(error = %err, credential_id = %cred_db_id, "failed to update passkey credential counter");
+                }
+            }
+            Err(err) => {
+                warn!(error = %err, "failed to serialize updated passkey credential");
+            }
         }
     }
 
     // Update last used timestamp
     let passkey_repo = state.passkey_repo.clone();
     tokio::spawn(async move {
-        let _ = passkey_repo.update_last_used(cred_db_id).await;
+        if let Err(err) = passkey_repo.update_last_used(cred_db_id).await {
+            warn!(error = %err, credential_id = %cred_db_id, "failed to update passkey last_used");
+        }
     });
 
     // Handle CLI callback flow
     if let Some(cli_info) = cli_callback {
         // Generate a bearer token for the CLI
-        let token_value = generate_token().map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        let token_value = generate_token().map_err(|err| {
+            error!(error = %err, "failed to generate CLI bearer token");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
         let token_hash_value = hash_token(&token_value);
         let new_token = NewToken::new(user_id, token_hash_value, cli_info.token_name);
-        state
-            .token_repo
-            .insert(new_token)
-            .await
-            .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        state.token_repo.insert(new_token).await.map_err(|err| {
+            error!(error = %err, "failed to store CLI bearer token");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
+
+        info!(user_id = %user_id, "CLI token created via passkey auth");
 
         let redirect_url = format!(
             "{}?token={}&state={}",
@@ -425,15 +457,20 @@ pub(crate) async fn passkey_add_start(
     Json(payload): Json<PasskeyAddStartRequest>,
 ) -> Result<Json<ChallengeResponse<CreationChallengeResponse>>, StatusCode> {
     let user = auth_user.0;
-    let webauthn_uuid =
-        Uuid::parse_str(&user.uuid).map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let webauthn_uuid = Uuid::parse_str(&user.uuid).map_err(|err| {
+        error!(error = %err, "failed to parse user UUID for passkey add");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
 
     // Load existing credentials to exclude (prevents re-registering same authenticator)
     let existing = state
         .passkey_repo
         .list_by_user(user.id)
         .await
-        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+        .map_err(|err| {
+            error!(error = %err, user_id = %user.id, "failed to list existing passkeys");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
 
     let exclude_credentials = existing
         .iter()
@@ -485,8 +522,10 @@ pub(crate) async fn passkey_add_finish(
             StatusCode::BAD_REQUEST
         })?;
 
-    let credential_json =
-        serde_json::to_string(&passkey).map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    let credential_json = serde_json::to_string(&passkey).map_err(|err| {
+        error!(error = %err, "failed to serialize new passkey credential");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })?;
     let new_credential = NewPasskeyCredential::new(user_id, credential_json, payload.name);
     state
         .passkey_repo