The European Union’s Carbon Border Adjustment Mechanism (CBAM) entered its definitive phase on January 1, 2026, pricing emissions embodied in imported goods. Existing leakage research examines production relocation across jurisdictions but overlooks leakage within a firm’s own operations. This paper identifies a previously unmodelled operational leakage mechanism arising from endogenous quality inspection. When a manufacturer simultaneously supplies a CBAM-regulated export market and an unregulated secondary market, imperfect inspection diverts conforming products to the secondary channel through Type-I errors, allowing their embodied emissions to escape border adjustment. We developed an integrated production-inspection pricing model, in which production rate, inspection reliability, replenishment cycle, and secondary market price are jointly optimised. Defect generation depends on production speed, inspection reliability is endogenous with a convex investment cost that rises sharply as reliability approaches unity, and market clearing determines the secondary price. Export-bound products incur the CBAM certificate price net of the free allocation benchmark, whereas secondary products face only the domestic carbon price. We established joint concavity of the profit function, proved that perfect inspection is never optimal, and derived the optimality condition governing inspection reliability. A key result shows that the marginal benefit of improving reliability decreased as the carbon price differential between regulated and unregulated markets widened. Numerical experiments parameterised to represent an Indian aluminium extrusion setting using published, engineering-estimated, and internally calibrated inputs showed that increasing CBAM stringency reduced optimal reliability, increased diversion of conforming output, and raised leaked emissions while leaving total emissions essentially unchanged. Benchmark comparisons with conventional carbon-aware inventory models showed that single-jurisdiction formulations predicted no operational leakage. Extending destination-based carbon pricing to the secondary market substantially restored inspection incentives and reduced leakage. We distinguished the baseline unpriced secondary-channel emissions under any regime from the smaller, policy-induced increment attributable specifically to CBAM stringency, and reported both.