critical-chain

name	critical-chain
description	Theory of Constraints 5 Focusing Steps, buffer management with 3-zone traffic light, relay runner execution discipline, WIP limits, and late start scheduling. Use when managing Goal execution pace, detecting bottlenecks, or when buffer status changes.
type	skill

Critical Chain & Buffer Management

When to Apply

• Managing Goal execution pace and timeline
• Buffer zone changes (GREEN/YELLOW/RED)
• Detecting and resolving bottlenecks
• Prioritizing which Actions to execute next
• When the founder asks "are we on track?"

Core Framework

TOC 5 Focusing Steps

Applied to the KPI tree. The Crux Driver (highest importance x tractability) is the constraint:

1. IDENTIFY: The Crux Driver is the constraint — most important AND most solvable bottleneck
2. EXPLOIT: Maximize that Driver's throughput. Execute its Actions first, eliminate waste, remove blockers. Never let constraint Actions wait.
3. SUBORDINATE: All other Drivers serve the constraint. Non-constraint Actions only execute when they don't compete for resources with constraint Actions.
4. ELEVATE: If Exploit is insufficient, propose additional investment (new Action types, budget, tools) for the constraint.
5. REPEAT: When the constraint moves (metric improves, another Driver becomes bottleneck), re-identify and restart.

Buffer Management (3-Zone Traffic Light)

Buffer sizing: Project Buffer = 50% of estimated time to achieve Goal.

Feeding buffers: Each non-constraint Driver has a small feeding buffer protecting the constraint. If a non-constraint Action delays, the feeding buffer absorbs it.

Zone	Buffer Consumed	Agent Behavior
GREEN (0-33%)	On track	Normal execution. Continue planned Actions. Light monitoring.
YELLOW (33-67%)	Falling behind	Investigate root cause. Generate recovery Actions. Notify user. Increase scan frequency.
RED (67-100%)	Significantly behind	Auto-propose high-impact recovery. Escalate to user. Deprioritize low-impact Drivers. Consider scope adjustment.

Buffer consumed: 45%  [========----------]
Goal progress:   34%  [======------------]
Status: YELLOW — buffer consumption outpacing progress

Buffer as early warning: Unlike milestone tracking (detects problems after deadline miss), buffer management provides continuous visibility. YELLOW at 20% progress gives weeks of lead time.

Relay Runner Principle

Three rules for Action execution:

1. Start immediately — When approved, execute in the very next chain invocation. No delay. (Prevents Student Syndrome — postponing when there's perceived slack.)
2. Full focus, one at a time — Constraint Driver Actions execute serially. Work one Action to completion before starting the next. (Prevents multitasking waste — context switching consumes 30-50% of capacity.)
3. Hand off immediately — On completion, move to verification and next Action with zero idle time. Early completion is celebrated. (Prevents Parkinson's Law — work expanding to fill time.)

WIP Limits

Scope	Max In Progress
Constraint Driver	1 Action at a time
Non-constraint Drivers	3 Actions concurrently
Total system	5 Actions across all Drivers

Late Start Scheduling

Non-constraint Driver Actions start as late as possible (while respecting feeding buffers). This reduces unnecessary WIP and keeps focus on the constraint.

Decision Rules

1. Constraint Actions never wait — always first priority, immediate execution
2. Buffer zone determines response intensity — GREEN: cruise. YELLOW: investigate. RED: escalate.
3. WIP limits are hard limits — do not exceed, even if capacity seems available
4. Relay runner is non-negotiable — no batching of constraint Actions, no multitasking
5. Re-identify constraint after every metric update — the bottleneck can shift
6. Subordination means saying no — non-constraint work that threatens constraint throughput is blocked

Anti-Patterns to Detect

Anti-Pattern	Signal	Response
Multitasking on constraint	Multiple constraint Actions in parallel	"Constraint Driver must have exactly 1 Action in progress. Serialize."
Student Syndrome	Approved Action not started for >24h	"Relay runner: start immediately on approval. No delay."
Ignoring buffer	Buffer RED but no escalation	"Buffer is RED — recovery Actions needed now."
Optimizing non-constraints	Heavy effort on non-bottleneck Drivers	"Effort on non-constraints has limited impact until the constraint is resolved."
WIP explosion	>5 Actions in progress simultaneously	"WIP limit exceeded. Complete or pause Actions before starting new ones."
Parkinson's Law	Action taking much longer than estimate	"Early completion is good. Hand off immediately — don't expand work to fill time."