perf: keyset/LATERAL SQL shapes, auth+blob-cache single-flight, spool buffers, DTO interning

Round 3 of benchmark-gated optimizations (benches/ROUND3.md; every change
gated by a before/after benchmark — an AFTER that did not beat its BEFORE
was to be rolled back; none needed it. Equivalence gates assert identical
row sequences / byte-identical output on every behavior-preserving rewrite):

DB hot paths (local PG16, EXPLAIN-verified):
- Web-UI listing (list_resources_paged): cursor pushed INSIDE the
  folders/files UNION-ALL branches as sargable row-value comparisons with
  per-branch ORDER/LIMIT + two partial expression indexes
  (folder_id, LOWER(name), id). 20k-entry folder: 26.6 -> 1.3 ms/page
  (19.5x); other sort modes at parity or better. New migration
  20260918000000. [benches/LISTING-KEYSET.md section in ROUND3]
- Photos timeline (list_media_files): per-drive CROSS JOIN LATERAL top-N
  on the timeline index, joins moved above the top-N. 50k-photo library:
  97.4 -> 1.6 ms/page (55.7x). The old "LIMIT stops the scan early"
  comment was refuted by EXPLAIN.
- PROPFIND sub-folders (both DAV surfaces): keyset list_folders_batch off
  idx_folders_unique_name replaces COUNT(*) OVER() + LIMIT/OFFSET
  (5k dirs: 79.7 -> 17.9 ms full walk, 4.5x).

Concurrency:
- Basic-auth cache single-flight (moka try_get_with): 8 concurrent DAV
  connections at TTL expiry paid 8 Argon2id runs (2.6 s CPU + 8x64 MiB);
  now 1 (300 ms). Failed verifications remain uncached.
- CachedBlobBackend per-hash single-flight + unique tmp names: 16
  concurrent cold readers = 16 full remote downloads racing truncating
  writes on ONE deterministic .tmp (corruptible cache); now 1 download
  (16x less egress, 2.8x wall on a shared link) and torn files can never
  be renamed into the cache.

I/O and allocations:
- Chunk-assembly reads 64K -> 512K buffers (2.3x, 8x fewer syscalls);
  chunk-spool writes via BufWriter 512K (5.6x, 32x fewer syscalls).
- S3/Azure put_blob_from_bytes_unsynced overrides: dedup settle no longer
  pays a HEAD probe per new chunk (2 RTT -> 1, 1.8x); Azure stops copying
  every chunk (Bytes -> Body, -0.44 ms - 4 MiB alloc per 4 MiB chunk).
- Entity->DTO mapping: Arc<str> interning of closed-set display fields +
  common MIMEs, 1-alloc etag/size formatting, FolderDto moves instead of
  clones. File row: 11 -> 4 allocs; folder row: 11.8 -> 1 (2.1x faster).
- CardDAV REPORT: deleted dead per-contact vCard pre-generation and the
  O(N^2) uid scan whose result was discarded (5k contacts: 55.7 -> 5.7 ms,
  9.8x); byte-identical XML asserted.
- Search-results cache: byte weigher + 32 MiB budget
  (OXICLOUD_SEARCH_CACHE_MAX_BYTES) replaces the 1000-ENTRY cap that let
  ~300 MiB of enriched rows sit in RSS; read latency parity.
- Dropped aws-config + aws-smithy-types (zero references; -82 dep-graph
  nodes, three SDK stacks gone from every build). tokio "process" is now
  an explicit feature (was enabled transitively by aws-config).

Frontend:
- Cached Intl.DateTimeFormat keyed by (locale, options) in formatDate and
  4 sibling callsites: 20k dates 2612 -> 51 ms (51.6x); vitest gate
  asserts output identity across locales and a 3x floor.

Validation: cargo fmt + clippy --all-features --all-targets -D warnings
clean; 518 unit + 548 integration-cfg tests green; new-shape endpoints
smoke-tested end-to-end over HTTP (all 5 listing sort modes with cursor
walks, WebDAV PROPFIND Depth-1, photos timeline, Basic-auth DAV login);
frontend npm run check clean, new vitest gates green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EBsU2qEzny3A8WQUEuMNCr

src/application/adapters/carddav_adapter.rs

@@ -651,7 +651,6 @@ impl CardDavAdapter {
     pub fn generate_contacts_response<W: Write>(
         writer: W,
         contacts: &[ContactDto],
-        vcards: &[(String, String)], // (uid, vcard_data)
         report: &CardDavReportType,
         base_href: &str,
     ) -> Result<()> {
@@ -672,17 +671,9 @@ impl CardDavAdapter {
 
         for contact in contacts {
             let href = format!("{}{}.vcf", base_href, contact.uid);
-            let vcard = vcards
-                .iter()
-                .find(|(uid, _)| *uid == contact.uid)
-                .map(|(_, data)| data.as_str())
-                .unwrap_or("");
+            // `write_contact_response` generates the vCard on demand when (and
+            // only when) address-data is actually requested.
             Self::write_contact_response(&mut xml_writer, contact, &props, &href)?;
-            // If address-data is requested, include vcard
-            if props.iter().any(|p| p.name == "address-data") || props.is_empty() {
-                // Already handled in write_contact_response
-            }
-            let _ = vcard; // suppress warning - used via contact_to_vcard fallback
         }
 
         xml_writer.write_event(Event::End(BytesEnd::new("D:multistatus")))?;
@@ -868,20 +859,25 @@ impl CardDavAdapter {
 
 /// Convert a ContactDto to vCard 3.0 format
 pub fn contact_to_vcard(contact: &ContactDto) -> String {
+    // `write!` into a String is infallible; `let _ =` discards the Ok(()).
+    // Formatting straight into the buffer avoids one temporary String per
+    // vCard line compared to `push_str(&format!(…))`.
+    use std::fmt::Write as _;
+
     let mut vcard = String::from("BEGIN:VCARD\r\nVERSION:3.0\r\n");
 
-    vcard.push_str(&format!("UID:{}\r\n", contact.uid));
+    let _ = write!(vcard, "UID:{}\r\n", contact.uid);
 
     if let (Some(last), Some(first)) = (&contact.last_name, &contact.first_name) {
-        vcard.push_str(&format!("N:{};{};;;\r\n", last, first));
+        let _ = write!(vcard, "N:{};{};;;\r\n", last, first);
     } else if let Some(last) = &contact.last_name {
-        vcard.push_str(&format!("N:{};;;;\r\n", last));
+        let _ = write!(vcard, "N:{};;;;\r\n", last);
     } else if let Some(first) = &contact.first_name {
-        vcard.push_str(&format!("N:;{};;;\r\n", first));
+        let _ = write!(vcard, "N:;{};;;\r\n", first);
     }
 
     if let Some(fn_name) = &contact.full_name {
-        vcard.push_str(&format!("FN:{}\r\n", fn_name));
+        let _ = write!(vcard, "FN:{}\r\n", fn_name);
     } else {
         // FN is mandatory in vCard 3.0
         let fn_name = format!(
@@ -892,68 +888,68 @@ pub fn contact_to_vcard(contact: &ContactDto) -> String {
         .trim()
         .to_string();
         if !fn_name.is_empty() {
-            vcard.push_str(&format!("FN:{}\r\n", fn_name));
+            let _ = write!(vcard, "FN:{}\r\n", fn_name);
         } else {
             vcard.push_str("FN:Unknown\r\n");
         }
     }
 
     if let Some(nickname) = &contact.nickname {
-        vcard.push_str(&format!("NICKNAME:{}\r\n", nickname));
+        let _ = write!(vcard, "NICKNAME:{}\r\n", nickname);
     }
 
     for email in &contact.email {
-        vcard.push_str(&format!(
+        let _ = write!(
+            vcard,
             "EMAIL;TYPE={}:{}\r\n",
             email.r#type.to_uppercase(),
             email.email
-        ));
+        );
     }
 
     for phone in &contact.phone {
-        vcard.push_str(&format!(
+        let _ = write!(
+            vcard,
             "TEL;TYPE={}:{}\r\n",
             phone.r#type.to_uppercase(),
             phone.number
-        ));
+        );
     }
 
     for addr in &contact.address {
-        let adr = format!(
-            ";;{};{};{};{};{}",
+        let _ = write!(
+            vcard,
+            "ADR;TYPE={}:;;{};{};{};{};{}\r\n",
+            addr.r#type.to_uppercase(),
             addr.street.as_deref().unwrap_or(""),
             addr.city.as_deref().unwrap_or(""),
             addr.state.as_deref().unwrap_or(""),
             addr.postal_code.as_deref().unwrap_or(""),
             addr.country.as_deref().unwrap_or(""),
         );
-        vcard.push_str(&format!(
-            "ADR;TYPE={}:{}\r\n",
-            addr.r#type.to_uppercase(),
-            adr
-        ));
     }
 
     if let Some(org) = &contact.organization {
-        vcard.push_str(&format!("ORG:{}\r\n", org));
+        let _ = write!(vcard, "ORG:{}\r\n", org);
     }
     if let Some(title) = &contact.title {
-        vcard.push_str(&format!("TITLE:{}\r\n", title));
+        let _ = write!(vcard, "TITLE:{}\r\n", title);
     }
     if let Some(notes) = &contact.notes {
-        vcard.push_str(&format!("NOTE:{}\r\n", notes.replace('\n', "\\n")));
+        let _ = write!(vcard, "NOTE:{}\r\n", notes.replace('\n', "\\n"));
     }
     if let Some(bday) = &contact.birthday {
-        vcard.push_str(&format!("BDAY:{}\r\n", bday.format("%Y-%m-%d")));
+        let _ = write!(vcard, "BDAY:{}\r\n", bday.format("%Y-%m-%d"));
     }
     if let Some(photo) = &contact.photo_url {
-        vcard.push_str(&format!("PHOTO;VALUE=URI:{}\r\n", photo));
+        let _ = write!(vcard, "PHOTO;VALUE=URI:{}\r\n", photo);
     }
 
-    vcard.push_str(&format!(
+    let _ = write!(
+        vcard,
         "REV:{}\r\n",
         contact.updated_at.format("%Y%m%dT%H%M%SZ")
-    ));
+    );
     vcard.push_str("END:VCARD\r\n");
 
     vcard

src/application/adapters/carddav_adapter_test.rs

@@ -484,10 +484,6 @@ mod tests {
     #[test]
     fn test_generate_contacts_response() {
         let contacts = vec![sample_contact()];
-        let vcards = vec![(
-            "contact-001".to_string(),
-            contact_to_vcard(&sample_contact()),
-        )];
         let report = CardDavReportType::AddressbookQuery {
             props: vec![
                 QualifiedName {
@@ -505,7 +501,6 @@ mod tests {
         let result = CardDavAdapter::generate_contacts_response(
             &mut output,
             &contacts,
-            &vcards,
             &report,
             "/carddav/ab-001",
         );
@@ -528,14 +523,12 @@ mod tests {
     #[test]
     fn test_generate_empty_contacts_response() {
         let contacts: Vec<ContactDto> = vec![];
-        let vcards: Vec<(String, String)> = vec![];
         let report = CardDavReportType::AddressbookQuery { props: vec![] };
 
         let mut output = Vec::new();
         let result = CardDavAdapter::generate_contacts_response(
             &mut output,
             &contacts,
-            &vcards,
             &report,
             "/carddav/ab-001",
         );