Say how big a session is before it is imported

The import list reported a line count, which is the wrong axis: these
transcripts embed screenshots as base64, so one line can be a megabyte.
On this machine a 69 MB session has 3,427 lines while a 44 MB one has
6,792 — the number on the row said nothing about what continuing the
session would cost, and size is the only thing there that predicts it.
The session behind the 2026-08-29 incident was 65 MB across 13,000 lines,
a line count that looks unremarkable.

Shown beside the line count rather than instead of it, since a short file
of long lines is exactly the expensive case. Not warned about and not
marked: importing a large session is a choice somebody is entitled to
make, and flagging it would be the interface nagging about a decision
already taken.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VETa8afmpWaYezLCqJhDB8

server/src/session/import.rs

@@ -67,6 +67,19 @@ pub struct Importable {
     /// Epoch seconds, for ordering by "what I was last doing".
     pub modified: f64,
     pub lines: usize,
+    /// Size of the file, in bytes.
+    ///
+    /// Reported because it is the only thing on a row that predicts what
+    /// continuing the session will cost, and lines do not: these
+    /// transcripts embed screenshots as base64, so one line can be a
+    /// megabyte. The session behind the 2026-08-29 incident was 65 MB
+    /// across 13,000 lines, which is a line count that looks unremarkable.
+    ///
+    /// Shown rather than warned about. Importing a large session is a
+    /// choice somebody is entitled to make, and marking it would be the
+    /// interface nagging about a decision already taken -- but they should
+    /// be able to see what they are taking on.
+    pub bytes: u64,
     /// Whether [`title`](Self::title) is a name somebody chose rather than
     /// something read out of the conversation. Sorted on, and worth the
     /// reader knowing: a name is a claim about what a session *is*, and a
@@ -151,7 +164,8 @@ if [ -d "$HOME/.claude/sessions" ]; then
 fi
 for f in "$HOME"/.claude/projects/*/*.jsonl; do
   [ -f "$f" ] || continue
-  printf '%s\t%s\t%s\t' "$(stat -c %Y "$f" 2>/dev/null || echo 0)" "$(wc -l < "$f")" "$f"
+  printf '%s\t%s\t%s\t%s\t' "$(stat -c %Y "$f" 2>/dev/null || echo 0)" \
+    "$(wc -l < "$f")" "$(stat -c %s "$f" 2>/dev/null || echo 0)" "$f"
   grep '"type":"custom-title"' "$f" 2>/dev/null | tail -1 | tr '\n' '\037'
   grep '"type":"user"' "$f" 2>/dev/null | grep -v '"tool_use_id"' | tail -12 | tr '\n' '\037'
   printf '\n'
@@ -190,9 +204,10 @@ done
 
 /// One line of [`list`]'s output, or nothing if it is not one.
 fn parse_row(line: &str) -> Option<Importable> {
-    let mut fields = line.splitn(4, '\t');
+    let mut fields = line.splitn(5, '\t');
     let modified: f64 = fields.next()?.trim().parse().ok()?;
     let lines: usize = fields.next()?.trim().parse().ok()?;
+    let bytes: u64 = fields.next()?.trim().parse().ok()?;
     let path = fields.next()?.to_string();
     let id = path.rsplit('/').next()?.strip_suffix(".jsonl")?.to_string();
 
@@ -238,6 +253,7 @@ fn parse_row(line: &str) -> Option<Importable> {
             .unwrap_or_else(|| "(no messages)".to_string()),
         modified,
         lines,
+        bytes,
         path,
     })
 }