Enhance tool documentation and add new features

- Added module-level documentation for memory tools (`remember`, `recall`, `forget`) to clarify their purpose.
- Improved documentation in `recall.rs` and `remember.rs` to describe the functionality and flow of memory entry operations.
- Updated `mod.rs` to include descriptions for the tool trait and execution context.
- Enhanced `plan.rs` with detailed comments on plan-mode signaling tools.
- Documented text search tools in `search.rs` to explain their functionality.
- Improved sequential-thinking tool documentation in `seqthink.rs`.
- Added safety filter documentation in `shell_filter` for credential and git operations.
- Enhanced utility tools documentation, including `cd`, `dir_cache_update`, and `todowrite`.
- Improved rendering documentation in view modules (`chat`, `markdown`, `status`, `workflow`) to clarify rendering flows and purposes.

src/app/runtime/shortsend.rs

@@ -1,9 +1,20 @@
+//! Short-send / message shaping: compacts long conversation histories so
+//! they fit within the provider's context window before being sent to the
+//! LLM API.
 use crate::dto::chat::message::ChatMessage;
 
 const MAX_WIRE_TOKENS: usize = 2_000_000;
 const MIN_MESSAGES_BEFORE_SHAPE: usize = 20;
 const ENGAGE_HYSTERESIS: usize = 5;
 
+/// Decide whether the message list should be shaped (compacted) before
+/// sending to the LLM.
+///
+/// Flow: skip shaping if fewer than `MIN_MESSAGES_BEFORE_SHAPE` messages
+/// → once past that threshold, use hysteresis (require 5 more messages
+/// before re-engaging if shaping is currently active) to avoid oscillation.
+///
+/// Return: `true` if shaping should be applied.
 pub fn should_shape(total_messages: usize, prev_shaped: bool) -> bool {
     if total_messages < MIN_MESSAGES_BEFORE_SHAPE {
         return false;
@@ -16,6 +27,19 @@ pub fn should_shape(total_messages: usize, prev_shaped: bool) -> bool {
     total_messages >= threshold
 }
 
+/// Compact a long message list by dropping middle messages and inserting
+/// a summary placeholder.
+///
+/// Flow: if the estimated token count is within budget, return messages
+/// unchanged → otherwise keep the system message and the most recent
+/// messages (up to `MAX_WIRE_TOKENS / 200` of them) with a `[prior
+/// conversation compacted]` system message in between.
+///
+/// Why: keeps context-size overhead roughly constant regardless of
+/// session length.
+///
+/// Return: a new Vec<ChatMessage> that preserves the first message and
+/// the tail.
 pub fn shape_messages(messages: &[ChatMessage], token_count: usize) -> Vec<ChatMessage> {
     if token_count <= MAX_WIRE_TOKENS || messages.len() < 10 {
         return messages.to_vec();