---
id: "bug-1565"
status: "fixed"
status_updated: "2026-09-24"
status_note: ""
component: "build"
severity: "unknown"
timestamp: "2026-08-17T07:16:00.000Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: ["src/tools/xce-build.sh (setup_build)"]
tags: ["xce-build.sh", "build-tooling", "footgun", "meson", "discovery"]
related: []
legacy: true
---

# bug-1565: src/tools/xce-build.sh's setup_build() does an unconditional `rm -rf "$BUILD_DIR"` + fresh `meson…

## Description
src/tools/xce-build.sh's setup_build() does an unconditional `rm -rf "$BUILD_DIR"` + fresh `meson setup` for EVERY component case (controller, worker, xceadmin, etc), not just when actually needed -- running `/xce-build xceadmin` (or any single-component target) after `/xce-build controller` in the SAME build dir silently deletes the already-built xce_controller/xce_test/etc binaries, leaving only that one component's fresh output. Discovered live while enhancing /xce-deploy-ha: a working xce_controller from an earlier turn vanished after an unrelated `/xce-build xceadmin` run in the same xce.build dir, breaking a live-deploy test with 'No such file or directory' for the controller binary.

## Environment
_Not recorded (migrated from buglog.json)._

## Reproduction
_Not recorded (migrated from buglog.json)._

## Root cause
setup_build() (xce-build.sh, called at the top of every component case branch) always does `rm -rf "$BUILD_DIR"; meson setup "$BUILD_DIR" ...` before compiling -- a full wipe-and-reconfigure regardless of which single component was requested. Since `meson compile -C "$BUILD_DIR" <component>` only rebuilds that one target afterward, every OTHER previously-built target in the same dir (e.g. xce_controller, when the requested component was xceadmin) is gone until something explicitly rebuilds it too. Not investigated further / not fixed -- out of scope for the /xce-deploy-ha enhancement session that found it; flagged here for whoever owns xce-build.sh next. A likely fix direction: only rm -rf+reconfigure when MESON_OPTS actually differ from the existing build dir's recorded options (or on first setup / explicit request), otherwise just `meson compile -C "$BUILD_DIR" <target>` against the existing configured dir.

## Fix
FIXED (opt-in, not a default-behavior change). Added --incremental to xce-build.sh (parsed out of the argument list before the existing component/profile/build_dir positional parsing, so it can appear anywhere and never disturbs that parsing). When passed AND the target build dir already has a build.ninja (i.e. it's already configured), setup_build() runs `meson setup --reconfigure "$BUILD_DIR" "${MESON_OPTS[@]}"` in place instead of `rm -rf` + fresh `meson setup` -- preserving any other already-built component's binaries in that dir. First-ever build of a dir (no build.ninja yet) still does a normal fresh setup regardless of the flag, since there's nothing to reconfigure. Default (flag omitted) is completely unchanged -- still always wipes. Deliberately NOT made the default: the known missing-dependency-edge races in the capnp-generation custom_target (see recurring buglog entries on 'controller.capnp.h: No such file or directory') are papered over by always wiping (worst case: a loud, retry-fixable clean-build failure); without the wipe the same gap could instead cause SILENT staleness (a schema edit not triggering regeneration, build reports success against stale generated code) -- an --incremental caller is explicitly opting into that tradeoff. Live-validated: built controller (xce_controller present), then `xceadmin --incremental` (wheel built, xce_controller's mtime unchanged -- survived); confirmed the flag works regardless of argument position (`--incremental xceadmin` and `xceadmin --incremental` both work); confirmed the DEFAULT (no flag) still wipes as before (xce_controller correctly gone after a plain `xceadmin` rebuild). Also updated the /xce-build skill and build-deployment.md steering doc to document the new flag.

## Verification
_Not recorded (migrated from buglog.json)._

## References
_Not recorded (migrated from buglog.json)._