A reconciliation loop continuously observes actual state,…

A reconciliation loop continuously observes actual state, compares it to desired state, and takes the minimum action to close the gap. If actual drifts — the loop corrects automatically.

Backlinks

Kubernetes docs formalize this as a reconciliation loop — observe, diff, actuate. →

Kubernetes has already implemented and standardized this pattern: any developer can define a custom desired state (CRD) and write a controller that continuously reconciles it with reality. →

Desired State Systems | System | Loop | Underlying API | |---|---|---| | NixOS | closed | OS packages and config (xettel) | | React | open | browser DOM | | Terraform | closed | cloud infrastructure | | Kubernetes | closed, continuous | container orchestration (xettel) | | GitOps for device fleets | closed | physical devices (bib) | →

GitOps for Fleet Management This is the same reconciliation loop that Kubernetes uses: observe actual state, compare to desired, actuate to close the gap. Applied here not to containers but to physical device fleets. →

Feedback Loops

Control Theory (Wikipedia) — overview of the field: Maxwell → PID → cybernetics → modern control (bib)
Open-Loop vs Closed-Loop Systems — the fundamental distinction: does the system re-check actual state?
Stability in Feedback Systems — overshoot, oscillation, settling time, steady-state error
PID Control — the canonical controller: proportional + integral + derivative
Controllability and Observability — prerequisites: can you steer it? can you see it?
Robustness in Control Systems — handling model imprecision and disturbance
2039567024205267136 — closed-loop feedback control: measure, compare, actuate
2039566010131558818 — Kubernetes reconciliation loop as a specific implementation
2039567945400254882 — Kubernetes' loop is Watt's governor (1788) applied to software
2039613059178873301 — dead band: the range where the controller deliberately does nothing

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Open-Loop vs Closed-Loop Systems

Open-loop — React assumes sole ownership of the DOM. It does not re-read actual DOM state; if another script mutates the DOM, React will not detect or fix it.
Closed-loop — Terraform checks actual infrastructure against the saved plan, detecting drift caused by manual changes or other tools.
Closed-loop, continuous — Kubernetes runs reconciliation controllers in a permanent loop. Delete a pod and the controller immediately recreates it (xettel, K8s docs).

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