> ## Documentation Index
> Fetch the complete documentation index at: https://fhenix-docs-deep-dive-rewrite.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Compute Pipeline

> The offchain components that carry an FHE task from onchain event to committed result

| Aspect               | Description                                                                                                                                                                     |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Type**             | Offchain execution pipeline, built from four components.                                                                                                                        |
| **Function**         | Carries every FHE task from onchain event to committed result.                                                                                                                  |
| **Responsibilities** | • Listens to TaskManager events on each host chain<br />• Validates and orders operations<br />• Executes them with the TFHE library<br />• Posts a commitment for every result |

The compute pipeline is the computation side of CoFHE. Contracts never call it. It subscribes to what happens onchain, does the encrypted math, and anchors the results.

Four components make up the pipeline. Each one owns a single step, and work moves in one direction.

```mermaid theme={null}
%%{init: {"theme": "base", "themeVariables": {"fontFamily": "Menlo, Monaco, Consolas, monospace", "fontSize": "16px", "primaryColor": "#8FBAF5", "primaryBorderColor": "#2E7CF6", "primaryTextColor": "#0A1626", "lineColor": "#4C8DFF", "signalColor": "#4C8DFF", "signalTextColor": "#8FA3BF", "actorBkg": "#8FBAF5", "actorBorder": "#2E7CF6", "actorTextColor": "#0A1626", "actorLineColor": "#3D4654", "noteBkgColor": "#14171C", "noteBorderColor": "#3D4654", "noteTextColor": "#AFC3DE", "activationBkgColor": "#1E3A5F", "activationBorderColor": "#4C8DFF", "clusterBkg": "#14171C", "clusterBorder": "#3D4654", "titleColor": "#E7EAEE", "edgeLabelBackground": "#8FBAF5", "textColor": "#AFC3DE", "labelTextColor": "#E7EAEE", "tertiaryColor": "#14171C", "loopTextColor": "#AFC3DE", "labelBoxBkgColor": "#1E3A5F", "labelBoxBorderColor": "#4C8DFF"}, "sequence": {"actorFontFamily": "Menlo, Monaco, Consolas, monospace", "messageFontFamily": "Menlo, Monaco, Consolas, monospace", "noteFontFamily": "Menlo, Monaco, Consolas, monospace", "width": 220, "actorFontSize": 16, "messageFontSize": 16, "noteFontSize": 15}}}%%
flowchart LR
    TM["TaskManager<br/>host chain"] --> SL["Slim listener<br/>reads chain events"]
    SL --> FO["FheOS<br/>validates and orders"]
    FO --> FE["FHE Engine<br/>computes on ciphertexts"]
    FE --> BP["Blockchain poster<br/>batches commitments"]
    BP --> CR["CommitmentRegistry<br/>registry chain"]
    FE <--> CTS[("Ciphertext store")]
```

## Slim listener

The slim listener watches TaskManager events on every host chain the pipeline serves. `TaskCreated` events bring FHE operations in for execution. `InputVerified` events bring verified encrypted inputs in, so a commitment gets anchored for each.

Delivery is reliable by construction. The listener tracks the last processed block, so a crash or a missed range is re-scanned rather than skipped.

## FheOS

FheOS checks that each operation is well formed and that the inputs it references exist. It holds the operation state for the pipeline.

Operations can arrive before the inputs they depend on have finished computing. FheOS defers such operations and releases them once the missing results land, so out-of-order arrival never produces a wrong answer. Work that is malformed, or that references inputs that never materialize, is set aside for inspection instead of being silently dropped.

## FHE Engine

The FHE Engine runs validated operations against the TFHE library: arithmetic, comparison, select, cast, and random generation on encrypted operands. It reads its operands from the ciphertext store and writes the result back.

The result ciphertext is stored under the handle the TaskManager issued. Any deferred operations waiting on that handle are released as soon as it lands.

Note the name. The FHE Engine is one component inside the compute pipeline, not the pipeline itself.

## Blockchain poster

For every stored result, the pipeline produces a commitment, the `keccak256` hash of the stored ciphertext bytes. The blockchain poster batches those commitments and posts them to the [CommitmentRegistry](/deep-dive/cofhe-components/commitment-registry) on the registry chain.

This is the anchor [Teecryptor](/deep-dive/cofhe-components/teecryptor) verifies before decrypting anything. Only bytes that hash to a registered commitment ever reach the decryption key.

## Key material

The pipeline computes with the FHE public key material only. Production builds load no decryption key, so a compromised pipeline can corrupt results (which commitment verification would catch) but cannot read them. Decryption capability exists solely inside [Teecryptor](/deep-dive/cofhe-components/teecryptor)'s attested enclave.