What
On the runner and bring-your-own-cloud execution path, CLAUDE_RUNNER_FAIL_FAST_FETCH makes a git fetch fail immediately instead of retrying, and CCR_DELTA_RESET makes the fetch record HEAD beforehand and treat the "Resolving deltas" 100% progress line as a point that resets the stall timer. Both are read as plain booleans from the environment.
Evidence
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Names in the bundleCLAUDE_RUNNER_FAIL_FAST_FETCHCCR_DELTA_RESET