Run the experiment
The erosion input is a compounding annual haircut to the labor-income base — the payroll levy's base and the wage share of the income tax together. For calibration: the entire post-1970 US labor-share decline averaged about 0.1% per year in these units, so 1%/yr sustained for five decades sits far outside historical experience.
Where the edges are
Bisected on this same engine (central scenario; the plateau test holds the corridor at its 29.0%/53.0% ceiling; horizon extended to 2115). World A — where capital captures half of what labor loses — has a plateau band rather than a threshold: roughly 0.8–6.1%/yr at the ruled coupling, because past the band's top the wealth-transfer registers compound fast enough to retire the debt again.
| Outcome | Erosion only | World B — stagnation |
|---|---|---|
| Retirement slips +10 years | 0.46%/yr | 0.24%/yr |
| Retirement slips +25 years | 0.53%/yr | 0.29%/yr |
| Debt plateaus at the corridor cap — Congress's call | 0.64%/yr | 0.34%/yr |
Zeroing immigration moves the retirement date by zero years — intake is demand-contingent by design (a visa exists only where domestic hiring fails at the domestic-equivalent wage), so the Accord's solvency asks nothing of anyone's border politics.
How to read what you just ran
Three honesty notes. First, the worst case is a scheduled public choice, not a spiral: past the plateau threshold the automatic correctors reach their legal limits, the debt holds roughly flat at the corridor ceiling, and the decision returns to Congress. Second, the thresholds include the ruled surplus symmetry — whenever the debt runs ahead of the fifty-year schedule, rates scale back toward the corridor floor, which returns money to taxpayers and spends some stress margin; both effects are in the numbers. Third, a run that retires the debt and then shows deficits reopening late-century is the model being honest about a permanent erosion that outlives the retirement — the readout flags it rather than hiding it.
Citation form for the retirement claim, here and anywhere these numbers travel: retired no later than 2079 by statute; central projection ~2052, decades ahead of the guarantee. The slips this laboratory measures are slips of the projection against that statutory ceiling.
Instrument provenance: the stress inputs, coupling presets, and bisection harness are in the published source (scripts/stress-scenarios.ts); the same engine produces every projection on the full scoring page and the master tables. At zero erosion this page shows exactly the published projections.