feat(dirty-content-fingerprint): worker shows fingerprint in --version

Worker's hand-rolled OPT_VERSION case now composes via a genuinely
separate version_display_buf/xce_compose_version_ex() call, mirroring
task 3.2's already-approved controller/scheduler pattern exactly. Both
startup-log XCECD_LOG call sites (--peers and no-peers) are left
completely untouched, same xce_compose_version() call, same version_buf.

Verified independently by review with a real build and live daemon runs
in both branches: --version shows <commit>-<fingerprint> matching
compile_commands.json, -dirty correctly stripped not doubled; both
startup log branches show the old fingerprint-less format unchanged.

All three C daemons (controller, scheduler, worker) are now complete.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.kiro/specs/dirty-content-fingerprint/tasks.md

@@ -18,7 +18,7 @@
   - _Requirements: 1.1, 1.2, 1.3, 5.1_
   - _Boundary: Nix packaging_
 
-- [ ] 3. Core: C daemon --version fingerprint display
+- [x] 3. Core: C daemon --version fingerprint display
 - [x] 3.1 Extend the shared version-composition mechanism with an optional fingerprint field, without touching commit_id
   - New sibling function `xce_compose_version_ex()` added alongside the completely untouched `xce_compose_version()` (zero diff lines in its body or its 3 pre-existing tests); anchors the `-dirty` strip via a true tail-slice `strcmp` (not `strstr`), so it cannot false-match a `-dirty` substring elsewhere; correctly appends `-<fingerprint>` with exactly one dash even when the commit field has no `-dirty` to strip; delegates via a genuine `return xce_compose_version(...)` call (not a re-implementation) when the fingerprint is empty/NULL, structurally guaranteeing byte-identical output, proven by a dedicated equivalence regression test
   - No `main.c` call sites were touched by this task (grep-confirmed all still call the original, untouched `xce_compose_version()`) -- that's tasks 3.2/3.3's job
@@ -33,9 +33,9 @@
   - _Boundary: controller/main.c, scheduler/main.c, controller/testsuite/test.c_
   - _Depends: 3.1_
 
-- [ ] 3.3 (P) Worker: fingerprint in --version, startup log unaffected
-  - Worker's hand-added `--version` case composes with the new `dirty_fingerprint` value; its startup INFO log line's composition call is left unchanged
-  - Observable confirmed live: on a dirty tree, `xcecd --version` shows the fingerprint suffix; both startup log branches remain byte-identical to the original feature's already-shipped format
+- [x] 3.3 (P) Worker: fingerprint in --version, startup log unaffected
+  - `OPT_VERSION`'s case now composes via a genuinely separate `version_display_buf`/`xce_compose_version_ex()` call, byte-for-byte mirroring task 3.2's already-approved controller/scheduler pattern (independently confirmed by review via direct diff comparison against commit `fd62e26`); both `XCECD_LOG` startup-log call sites (`--peers` and no-`--peers`) left completely untouched, same `xce_compose_version()` call, same `version_buf`
+  - Observable confirmed live (independently re-verified by review, real build + live daemon runs in both branches): `xcecd --version` shows `<commit>-<fingerprint>` matching `compile_commands.json` exactly, `-dirty` correctly stripped not doubled; both startup log branches show the old fingerprint-less `<commit>-dirty` format unchanged
   - _Requirements: 1.1, 1.2, 1.3, 1.4, 2.1, 3.1, 3.2, 4.1_
   - _Boundary: worker/main.c_
   - _Depends: 3.1_

src/worker/src/main.c

@@ -323,6 +323,16 @@ int main(int argc, char* argv[])
      * read this SAME buffer, never recomputing it independently, so the
      * two can never disagree (Requirement 2.2). */
     static char version_buf[128];
+    /* dirty-content-fingerprint task 3.3: SEPARATE buffer/composition, used
+     * ONLY for the --version case below. version_buf above is left
+     * completely untouched -- its own xce_compose_version() call and the
+     * two mutually-exclusive startup INFO log lines reading it (further
+     * down) are unaffected by this feature, per Requirement 3.2. This
+     * divergence (the two call sites now showing different strings) is
+     * deliberate, not an oversight -- mirrors controller/main.c's and
+     * scheduler/src/main.c's identical version_display_buf pattern
+     * (dirty-content-fingerprint task 3.2). */
+    static char version_display_buf[128];
     xce_cluster_config_t         cluster_cfg        = {0};
     int                          use_ha             = 0; /* 1 when --peers given */
 
@@ -378,6 +388,15 @@ int main(int argc, char* argv[])
      * ready by the time the startup INFO log lines run later in main(). */
     xce_compose_version(version_buf, sizeof(version_buf), "xce v0.0.1-",
                         STR(VERSION_COMMIT_ID), STR(VERSION_BUILD_TIME));
+    /* dirty-content-fingerprint task 3.3: --version-only composition --
+     * appends the dirty_fingerprint suffix (if any) on top of the same
+     * commit/build_time inputs. Do NOT fold this into version_buf above; the
+     * startup INFO log lines must keep showing the original, fingerprint-
+     * less format (Req 3.2). */
+    xce_compose_version_ex(version_display_buf, sizeof(version_display_buf),
+                           "xce v0.0.1-", STR(VERSION_COMMIT_ID),
+                           STR(VERSION_BUILD_TIME),
+                           STR(VERSION_DIRTY_FINGERPRINT));
 
     while ((opt = getopt_long(argc, argv, "n:l:vh", long_opts, NULL))
            != -1) {
@@ -402,8 +421,11 @@ int main(int argc, char* argv[])
         case OPT_VERSION:
             /* Prints and exits before any other startup work (peer
              * parsing, check_user(), daemon init, etc.) -- same contract
-             * as controller/scheduler's --version. */
-            printf("%s\n", version_buf);
+             * as controller/scheduler's --version. dirty-content-fingerprint
+             * task 3.3: prints version_display_buf (fingerprint-aware), not
+             * version_buf -- the startup INFO log lines further down keep
+             * reading the original version_buf, untouched. */
+            printf("%s\n", version_display_buf);
             return 0;
         case 'h':
         default: