Every demo above is Claude Code running inside four user-authored layers. Miss one and the system collapses back to stateless chat. Every business needs all four, tuned to how that business actually works.

A plain-text file Claude reads on every tool call. Principles, routing, what to file where, what to check first. It's where the durable shape of your work lives. It scopes from global to project, and when a topic grows past a few lines it breaks out into its own file under .claude/rules/ — same always-on behavior, one chapter per file, path-scoped so nothing clutters unrelated work.

Never use --no-verify to skip hooks.
Ask before destructive ops (rm -rf,
  force push, dependency removal).
Default to the naive option.
No em dashes in prose or commits.

Tailwind only. No custom CSS files.
Copy lives in Cortex. Don't rewrite
  pitch copy here; edit the spec.
Budget: 300KB gzipped JS.

// from pushback.md
Verdict first, then reasoning.
"That won't scale because Y."
Not "Interesting, but have you considered..."

Consequence: you stop re-explaining your standards every session. The next one starts already knowing them. Consistent behavior across projects, across topic shifts, across a year of work.

Reusable workflows in .claude/skills/. Each has a "Use when X" description. Claude matches your prompt against those descriptions and loads only what fires. Roughly an order of magnitude cheaper than equivalent MCPs because nothing runs until it triggers.

• session-start Orient from recent journals. Reads per-project state, self-heals gaps from transcripts.
• capture-and-record Save URLs, observations, testable beliefs the moment they surface. No prompting required.
• log-decision Record a choice between alternatives with the reasoning. Retrievable six months later.
• fanout-synthesis Spawn 2-5 parallel subagents on distinct slices of a landscape, then synthesize one report.
• conduct-review Systematic evaluation of an internal artifact. Findings and recommendations, not execution.

Consequence: procedures stop needing re-derivation. The right steps run the right way, every time the trigger fires.

External systems Claude calls through. Each MCP server exposes typed tools Claude invokes inside the conversation. Gmail to draft mail. Calendar to schedule. Obsidian to query your vault. Chrome DevTools to drive a real browser.

• obsidian Dataview queries over your notes, semantic search, patch frontmatter without re-reading the file.
• gmail Draft replies, scan threads, manage labels. The email is the tool, not a copy-paste target.
• calendar · drive Schedule work against real availability. Pull source documents Claude can read directly.
• chrome-devtools Drive a browser, run Lighthouse, inspect live pages. Test your own site while building it.

// actual call Claude makes, mid-conversation
search_vault({
  queryType: "dataview",
  query: "TABLE status FROM 'Projects'
          WHERE type = 'task' AND priority = 'A'
          AND !completed"
})

Consequence: Claude acts on your systems, not just talks about them. The operation is the conversation.

Sub-agents with isolated context. Main Claude delegates; results come back without polluting the primary conversation. Each agent has its own tool whitelist and its own model tier. You can spawn several in parallel.

• Explore Fast codebase surveys, pattern searches, open-ended questions across many files.
• bulk-mechanical Well-specified repeating edits across many files. Renames, frontmatter patches, schema sweeps.
• vault-scanner Hygiene passes across the vault. Broken links, frontmatter validation, orphaned notes.
• web-researcher One leg of a multi-source investigation. Five running in parallel, each on a distinct slice.
• Plan Architecture strategy. Implementation plans, trade-off analysis, step-by-step designs.

Consequence: parallelizable work runs parallel. Long searches don't burn your context budget. Fresh-head reviews actually come from a fresh head.

The knowledge didn't decay. It compounded.