Designer & builder

Tightrope

Keeping a backend and frontend in sync

[ PASS ][ FAIL ][ ERROR ]

Harrison Halperin

Project brief

Prototype

Problem

Backend and frontend contracts drift, especially when they live in different repositories.

Outcome

When a backend and frontend drift out of contract, this CLI catches it in CI (split repos or monorepo) and returns a machine-readable verdict.

Evidence

Static, schema-sync, and runtime checks change nothing, safe to run in CI.
Any failing check flips the verdict and can skip expensive runtime stages.

Key decisions

Judge zone: Static, schema-sync, and runtime checks change nothing, safe to run in CI.
Gate zone: Any failing check flips the verdict and can skip expensive runtime stages.
Fix zone: Agents draft remediation; humans apply. Scripts judge, agents fix.
Output: Machine-readable report with exit codes for pass, fail, and error states.

Where the drift happens

Backend and frontend contracts drift, especially when they live in different repositories. I built a CLI that catches that drift in CI and returns a machine-readable verdict.

The verification stack

Deterministic checks do the judging: schema sync, version alignment, runtime shape. They’re safe to run in CI because they change nothing.

Verification stack

01Changed filesgit diff or explicit list

02Classifysides + affected routes

03Static checkscontract + wiring scripts

04Schema syncgatedry-run alignment

05Runtime checksgatescoped test suites

06ReportJSON verdict + exit code

Changed files are classified, static and schema-sync checks run first, and expensive runtime checks only run when the verdict is still passing.

Judge zoneStatic, schema-sync, and runtime checks change nothing, so they’re safe to run in CI.

Gate zoneAny failing check flips the verdict and can skip expensive runtime stages.

The remediate path

When something’s off, a Cursor-SDK agent proposes the fix, but a human still applies it. Scripts judge, agents fix. It’s the same trust boundary Agent CI/CD draws at the merge level, applied here to contract checks instead.

Remediate path

1Failed verdict

2Build hintactionable context

3Agent draftproposed fix only

4Human applygate

When checks fail, a remediation hint is built. The agent path proposes fixes; a human still applies them.

Fix zoneAgents draft remediation; humans apply. Scripts judge, agents fix.

Edit vs merge is the authority version of the same boundary.

Reading the verdict

Machine-readable report with exit codes for pass, fail, and error states.

[ PASS ]pass

[ FAIL ]fail

[ ERROR ]error

Tooling & discipline

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