perf: round 22 — hot-GET HeaderMap borrow, native-WebDAV/CalDAV etag borrowed quotes, FileDto content_hash move, CalendarEvent stamp, ShareItemType case-fold

Benchmark-gated, same rule as ROUND2-21: every change ships with a
BEFORE/AFTER counting-allocator benchmark and a byte/-value equivalence
gate; an AFTER that fails to reduce allocations exits non-zero (rollback).
See benches/ROUND22.md and examples/bench_round22_micro.rs. All arms
no-Postgres.

- H1: the hot GET handlers (get_thumbnail, download_file, list_files_query,
  list_photos, NextCloud preview, public-share download/access) take
  `req: Request` last and read `req.headers()` by borrow instead of axum's
  HeaderMap extractor, whose FromRequestParts impl clones the whole request
  header table just to read 1-3 headers (the ROUND14 §A4 middleware pattern,
  finally propagated to the handlers). 2 -> 0 allocs/req · 9.95x wall.
- W1: native WebDAV write_etag_quoted — the etag emitter for every /webdav/
  PROPFIND row (per file AND per folder, up to 500/page) — emits the quotes
  as borrowed pre-escaped " text events instead of escaping a "{etag}"
  String (the ROUND20 §C1 / ROUND21 §R4 pattern). 3 -> 0 allocs/row.
- C1: CalDAV getetag routed through a shared write_quoted_etag helper across
  all 5 sites (3 per-event + 2 per-calendar); the now-dead etag: &mut String
  buffer threaded through write_event_response/standard/requested props + the
  two per-page buffers removed. 2 -> 0 allocs/row.
- D1: FileDto::from reuses the moved parts.blob_hash instead of cloning it
  via the content_hash() getter (the ROUND19/20 move-not-clone sweep missed
  it — hash/etag are read before into_parts()). Per file row of every
  listing. 1 -> 0 allocs/row.
- E1: CalendarEvent::update_time_range/update_all_day stamp timed
  DTSTART/DTEND via fmt::compact_ical_utc stack render (chrono fallback out
  of range) instead of the %Y%m%dT%H%M%SZ strftime interpreter. 4 -> 0.
- S1: ShareItemType::try_from uses eq_ignore_ascii_case instead of a
  throwaway to_lowercase() String. 1 -> 0 allocs/parse.

Verified: cargo clippy --features bench --all-targets -D warnings clean,
cargo fmt --all --check clean, cargo test --lib --features bench = 529
passed / 0 failed (incl. the OpenAPI-spec-validity test guarding the H1
utoipa-handler signature change).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DKyQ4AnYtgp1JtjzweyMeo

src/domain/entities/calendar_event.rs

@@ -575,21 +575,38 @@ impl CalendarEvent {
         self.end_time = end_time;
         self.updated_at = Utc::now();
 
-        // Update iCalendar data
-        let start_str = if self.all_day {
-            format!("{}T000000Z", start_time.format("%Y%m%d"))
+        // Update iCalendar data. Timed events stack-render the compact UTC
+        // stamp via `fmt::compact_ical_utc` (the ROUND19 §V2 pattern: drops
+        // chrono's `%Y%m%dT%H%M%SZ` strftime interpreter — ~3 → 0 allocs each),
+        // with chrono kept as the out-of-range fallback. All-day keeps its
+        // `%Y%m%d` + literal-suffix form. Byte-identical output either way.
+        let (mut sbuf, mut ebuf) = ([0u8; 16], [0u8; 16]);
+        let (start_owned, end_owned);
+        let start_str: &str = if self.all_day {
+            start_owned = format!("{}T000000Z", start_time.format("%Y%m%d"));
+            &start_owned
+        } else if let Some(s) =
+            crate::common::fmt::compact_ical_utc(&mut sbuf, start_time.timestamp())
+        {
+            s
         } else {
-            format!("{}", start_time.format("%Y%m%dT%H%M%SZ"))
+            start_owned = format!("{}", start_time.format("%Y%m%dT%H%M%SZ"));
+            &start_owned
+        };
+        let end_str: &str = if self.all_day {
+            end_owned = format!("{}T000000Z", end_time.format("%Y%m%d"));
+            &end_owned
+        } else if let Some(e) =
+            crate::common::fmt::compact_ical_utc(&mut ebuf, end_time.timestamp())
+        {
+            e
+        } else {
+            end_owned = format!("{}", end_time.format("%Y%m%dT%H%M%SZ"));
+            &end_owned
         };
 
-        let end_str = if self.all_day {
-            format!("{}T000000Z", end_time.format("%Y%m%d"))
-        } else {
-            format!("{}", end_time.format("%Y%m%dT%H%M%SZ"))
-        };
-
-        self.update_ical_property("DTSTART", &start_str);
-        self.update_ical_property("DTEND", &end_str);
+        self.update_ical_property("DTSTART", start_str);
+        self.update_ical_property("DTEND", end_str);
 
         Ok(())
     }
@@ -603,21 +620,37 @@ impl CalendarEvent {
         self.all_day = all_day;
         self.updated_at = Utc::now();
 
-        // Update iCalendar data
-        let start_str = if all_day {
-            format!("VALUE=DATE:{}", self.start_time.format("%Y%m%d"))
+        // Update iCalendar data. Timed events stack-render the compact UTC
+        // stamp via `fmt::compact_ical_utc` (drops chrono's `%Y%m%dT%H%M%SZ`
+        // strftime interpreter — ~3 → 0 allocs each), chrono fallback out of
+        // range. All-day keeps its `VALUE=DATE:` + `%Y%m%d` form. Byte-identical.
+        let (mut sbuf, mut ebuf) = ([0u8; 16], [0u8; 16]);
+        let (start_owned, end_owned);
+        let start_str: &str = if all_day {
+            start_owned = format!("VALUE=DATE:{}", self.start_time.format("%Y%m%d"));
+            &start_owned
+        } else if let Some(s) =
+            crate::common::fmt::compact_ical_utc(&mut sbuf, self.start_time.timestamp())
+        {
+            s
         } else {
-            format!("{}", self.start_time.format("%Y%m%dT%H%M%SZ"))
+            start_owned = format!("{}", self.start_time.format("%Y%m%dT%H%M%SZ"));
+            &start_owned
+        };
+        let end_str: &str = if all_day {
+            end_owned = format!("VALUE=DATE:{}", self.end_time.format("%Y%m%d"));
+            &end_owned
+        } else if let Some(e) =
+            crate::common::fmt::compact_ical_utc(&mut ebuf, self.end_time.timestamp())
+        {
+            e
+        } else {
+            end_owned = format!("{}", self.end_time.format("%Y%m%dT%H%M%SZ"));
+            &end_owned
         };
 
-        let end_str = if all_day {
-            format!("VALUE=DATE:{}", self.end_time.format("%Y%m%d"))
-        } else {
-            format!("{}", self.end_time.format("%Y%m%dT%H%M%SZ"))
-        };
-
-        self.update_ical_property("DTSTART", &start_str);
-        self.update_ical_property("DTEND", &end_str);
+        self.update_ical_property("DTSTART", start_str);
+        self.update_ical_property("DTEND", end_str);
     }
 
     /**

src/domain/entities/share.rs

@@ -180,13 +180,18 @@ impl TryFrom<&str> for ShareItemType {
     type Error = ShareError;
 
     fn try_from(s: &str) -> Result<Self, Self::Error> {
-        match s.to_lowercase().as_str() {
-            "file" => Ok(ShareItemType::File),
-            "folder" => Ok(ShareItemType::Folder),
-            _ => Err(ShareError::ValidationError(format!(
+        // ASCII case-insensitive compare against the two literals instead of a
+        // throwaway Unicode `to_lowercase()` String — byte-identical acceptance
+        // for the ASCII targets "file"/"folder" (1 → 0 allocs/call).
+        if s.eq_ignore_ascii_case("file") {
+            Ok(ShareItemType::File)
+        } else if s.eq_ignore_ascii_case("folder") {
+            Ok(ShareItemType::Folder)
+        } else {
+            Err(ShareError::ValidationError(format!(
                 "Invalid item type: {}",
                 s
-            ))),
+            )))
         }
     }
 }