feat: add agent diary collection for session logging

[Copilot]

Description

Agents now maintain session diaries documenting goals, key actions, and learnings. Diaries display on homepage between Posts and Notes.

Changes Made

• AGENTS.md - Added diary-keeping directive with format spec (frontmatter, required sections, optional post cross-referencing)
• src/diary/ - New collection directory following tag-based pattern from src/posts/
• src/diary/2026-02-03-implementing-agent-diary-feature.md - Example entry demonstrating structure
• src/_includes/layouts/home.njk - Added diary collection render between posts and notes

Diary entry structure:

---
title: "Session Description"
description: "What was accomplished"
date: YYYY-MM-DD
layout: layouts/content.njk
tags:
  - diary
relatedPosts: # Optional
  - /posts/post-slug/
---

## Session Goals
## Key Actions  
## Reflections

Checklist

• Code follows engineering principles (simplicity, smallest possible change)
• Site builds successfully (npm run build:prod)
• Changes tested locally (npm start)
• Documentation updated (if needed)
• No unnecessary dependencies added
• Changes are minimal and focused

Screenshots (if applicable)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Post agent logs</issue_title>
<issue_description>## Context

I think it would be interesting to have an agent. Keep logs while working on the site that also get posted somewhere on the site.

Proposed Solution

Set a directive in the agents.MD file that requires all agents to keep a diary. The diary would be a marked down file written to the appropriate collections folder in the site.

The site would have a collection called diary that an agent would write to for every session it was working in. During the session it would keep track of key actions. It was taking for each of those actions. It would include why it chose its particular approach and what outcome it was seeking to achieve. Before the end of the session, it would reflect back on what it learned while doing the work.

These sessions would be visible summer on the homepage of the site juxtaposed with the current posts I have written. when an agent is helping me write a post the diary from that session will be cross-referenced or linked on my post

Definition of Done

• Feature is implemented
• Changes are documented (if applicable)
• Site builds without errors
• Changes are tested locally
• Code follows simplicity principles

Additional Context

Comments on the Issue (you are @copilot in this section)

• Fixes Post agent logs #110

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[cloudflare-workers-and-pages]

Deploying benkutil-github-io with    Cloudflare Pages

Latest commit:	e43641f
Status:	✅  Deploy successful!
Preview URL:	https://011a56da.benkutil-github-io.pages.dev
Branch Preview URL:	https://copilot-add-agent-logs-featu.benkutil-github-io.pages.dev

View logs