Learn Claude Code

Learning Path

s01 to s17: Progressive Agent Harness Design

Layer Legend

Tools & Execution
Planning & Control
Memory Management
Concurrency & Scheduling
Multi-Agent Platform
01
s01Minimal model/tool loop

The Agent LoopOne Loop Is All You Need

106 lines of code1 tools

“The smallest useful agent is a loop that calls the model, runs tools, and feeds results back.”

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02
s02Tool dispatch map

Tool UseAdd a Tool, Add Just One Line

149 lines of code5 tools

“The loop stays stable while capabilities register into a dispatch table.”

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03
s03Permission gate

PermissionCheck Permissions Before Execution

185 lines of code5 tools

“Dangerous actions need a harness decision point before the shell runs.”

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04
s04Lifecycle hooks

HooksHang on the Loop, Don't Write into It

207 lines of code5 tools

“Cross-cutting behavior belongs around the loop, not tangled inside it.”

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05
s05Todo manager

TodoWriteAn Agent Without a Plan Drifts Off Course

284 lines of code6 tools

“Explicit plans keep long-running work visible and correctable.”

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06
s06Isolated subtask context

SubagentBreak Large Tasks into Small Ones with Clean Context

291 lines of code6 tools

“Subagents give each subtask a clean message history while preserving the main thread.”

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07
s07On-demand skill loader

Skill LoadingLoad Only When Needed

306 lines of code6 tools

“Inject specialized knowledge only when the task actually needs it.”

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08
s08Context compaction

Context CompactContext Will Fill Up

503 lines of code5 tools

“Compression keeps the conversation usable when the context window gets crowded.”

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09
s09Durable memory layer

MemoryKeep a Layer That Doesn't Lose Details

679 lines of code5 tools

“Some facts should survive summarization and future sessions.”

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10
s10Task board

Task SystemBreak Big Goals into Small Tasks

466 lines of code11 tools

“A task graph turns vague goals into ordered, observable work.”

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11
s11Background execution

Background TasksSlow Operations Go to the Background

404 lines of code5 tools

“The agent can keep reasoning while slow work completes elsewhere.”

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12
s12Scheduled task creation

Cron SchedulerProducing Work on a Schedule

642 lines of code5 tools

“Recurring work should be created by the harness, not remembered by the model.”

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13
s13Team runtime with task-bound worktrees

Agent Team RuntimePersistent Teammates, Atomic Claims, Task-Bound Worktrees

1592 lines of code5 tools

“Persistent teammates can reliably discover and execute parallel work when the runtime owns messaging, atomic claims, and task-bound working directories.”

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14
s14MCP tool bridge

MCP ToolsExternal Tools, Standard Protocol

444 lines of code5 tools

“External services can become agent tools through a standard discovery and call protocol.”

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15
s15Integrated harness

Integrated HarnessMany Mechanisms, One Loop

2770 lines of code26 tools

“The integrated harness is still one loop, surrounded by the systems introduced across the course.”

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16
s16Resumable workflow runtime

Workflow RuntimeScripts Own Fixed Orchestration

725 lines of code27 tools

“When orchestration has a fixed shape, code can make it parallel, deterministic, and resumable.”

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17
s17Goal completion gate

Goal LoopIndependent Evaluation Decides When to Stop

794 lines of code5 tools

“A durable goal keeps the loop working until an independent evaluator finds the completion condition satisfied in the conversation.”

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LOC Growth

s01
106
s02
149
s03
185
s04
207
s05
284
s06
291
s07
306
s08
503
s09
679
s10
466
s11
404
s12
642
s13
1592
s14
444
s15
2770
s16
725
s17
794