Peer code review found multiple panic-reachable paths:
1. serde_json::to_string().unwrap() in 4 robot-mode output functions
(who.rs, main.rs x3). If serialization ever failed (e.g., NaN from
edge-case division), the CLI would panic with an unhelpful stack trace.
Replaced with unwrap_or_else that emits a structured JSON error fallback.
2. encode_rowid() in chunk_ids.rs used unchecked multiplication
(document_id * 1000). On extreme document IDs this could silently wrap
in release mode, causing embedding rowid collisions. Now uses
checked_mul + checked_add with a diagnostic panic message.
3. HTTP response body truncation at byte index 500 in client.rs could
split a multi-byte UTF-8 character, causing a panic. Now uses
floor_char_boundary(500) for safe truncation.
4. who.rs reviews mode: SQL used `m.author_username != ?1` which silently
dropped MRs with NULL author_username (SQL NULL != anything = NULL).
Changed to `(m.author_username IS NULL OR m.author_username != ?1)`
to match the pattern already used in expert mode.
5. handle_auth_test hardcoded exit code 5 for all errors regardless of
type. Config not found (20), token not set (4), and network errors (8)
all incorrectly returned 5. Now uses e.exit_code() from the actual
LoreError, with proper suggestion hints in human mode.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>