Flight Plan: Emacs Client UX Overhaul

Phase A: Demand (Verify State)

Current state: The `opencortex` Emacs client uses a single buffer for both input and output, or a clunky side-window for reasoning. The interface is rudimentary and lacks modern chat application affordances.
User feedback indicates that responses and reasoning streams are sometimes missing or hard to read.
Objective: Design a comprehensive, intuitive, and modern UX for the Emacs client.

Dedicated Input Area: A text box (minibuffer or dedicated window at the bottom) for user input, distinct from the chat history.
Main History Buffer: A primary buffer displaying the conversation history, agent outputs, and system logs.
Syntax Highlighting: Enhanced colorization depending on the syntax (e.g., Lisp code, shell commands, Org-mode elements).
Diff Visualization: Clear, visual representation of proposed code changes or diffs, akin to modern CLI tools (e.g., `gemini-cli` or `magit`).
Overall Appeal: A comprehensive design that feels modern and intuitive for users accustomed to tools like Claude Code or ChatGPT interfaces.

We will abandon the single-buffer approach and adopt a dual-window layout for the chat interface:

`*opencortex-chat*` (Top, 80% height): A read-only `special-mode` or customized `org-mode` buffer dedicated to displaying the conversation history, agent responses, and tool execution logs.
`*opencortex-input*` (Bottom, 20% height): A dedicated `markdown-mode` or `org-mode` buffer for composing messages. Pressing `C-c C-c` here will send the contents to the daemon, clear the input buffer, and append the user's message to the main chat buffer.

To make the main chat buffer appealing, we need a robust formatting engine within `opencortex.el`:

Structured Insertion: When the daemon sends an `:insert-at-end` command, the Emacs client will parse the payload.
Font-Lock Extensions: We will define custom `font-lock` rules for the `*opencortex-chat*` buffer to highlight specific elements:
- User Messages: Distinct background or font face.
- Agent Responses: Standard Org-mode styling.
- Tool Executions (Reasoning): Dimmed or italicized text for "Thinking…" or "Executing shell command: `ls`".
- Code Blocks: Native syntax highlighting for `#+begin_src` blocks using `org-src-fontify-natively`.

To handle code modifications safely and beautifully:

When the agent proposes a file change, it will send a structured `:diff` or `:patch` payload rather than raw text.
The Emacs client will intercept this payload and present it using `diff-mode` or a custom overlay within the chat buffer, providing visual red/green highlights for removals and additions.
Interactive Acceptance: The user can press a key (e.g., `C-c C-y`) on the diff to accept and apply the patch, realizing the "Active Approval Mode" pattern in Emacs.

Instead of a separate right-side window that clutters the workspace, the reasoning stream (Probabilistic Engine thoughts, tool calls) will be integrated directly into the main `*opencortex-chat*` buffer.
It will be presented as a collapsible Org-mode drawer (e.g., `:REASONING:`) or formatted as dimmed, transient text that provides transparency without overwhelming the primary conversation.

Launch `M-x opencortex`.
Verify the dual-window layout appears correctly.
Type a message in the input buffer, send it, and verify it clears and appears in the main buffer.
Trigger a tool call and verify the reasoning stream is formatted clearly (and distinct from the final answer).
Trigger a file modification and verify the diff visualization is presented elegantly.

This overhaul requires significant changes to:

`projects/opencortex/src/opencortex.el` (The Emacs client).
`notes/org-skill-chat.org` (To update the expected payload formats if we move beyond simple `:insert-at-end`).