~anthropic/claude-sonnet-latest → A (85:15)

Side A is a coherent, real fix: it removes a silently-defaulting `.unwrap_or(0)` fallback for thread_post_index in favor of an explicit `expect` that surfaces bugs, fixes the corresponding UI/link logic, updates doc comments to match 0-based semantics, and adds regression tests verifying the new indexing behavior end-to-end. Side B is a dump of large, mostly unrelated file snapshots (including literal shell-prompt lines like 'tommy@Tommys-Laptop:...⇒ cat ...' pasted into the diff), design notes/tdsl files, and whole modules added wholesale with no clear incremental change being reviewed, making it noisy and hard to attribute as a meaningful single commit of lasting value.