त्वं चाहं च दुर्गं कारयावहे इति कर्मसंधिः ॥ कZ_०७.१२.०१ ॥
tvaṃ cāhaṃ ca durgaṃ kārayāvahe iti karmasaṃdhiḥ
“त्वं चाहं च दुर्गं कारयावहे” इति कर्मसन्धिः ।
A pact defined by a concrete joint undertaking—here, co-constructing a fort—so cooperation is enforced by shared costs and shared outputs.