fix: shell hook test suite passes with no ambient git identity

hooks/_lib.sh

@@ -168,7 +168,13 @@ _tl_compute_data_root() {
   _tl_main=$(git -C "$_tl_wt_canonical" worktree list --porcelain 2>/dev/null \
     | awk '/^worktree /{print substr($0,10); exit}')
   if [ -z "$_tl_main" ] || [ ! -d "$_tl_main" ]; then
-    printf '%s' "$_tl_wt"
+    # Canonicalized, like every other return path in this function (issue
+    # #42 review finding): a caller that compares this return value against
+    # a separately-canonicalized tl_root() - as session-onboard.sh's
+    # worktree-sharing note does - needs both sides consistently resolved,
+    # or a raw path here reads as "different location" purely from a
+    # symlink (macOS /tmp vs /private/tmp) even when it's the same one.
+    printf '%s' "$_tl_wt_canonical"
     return
   fi
   # Canonicalize the main worktree path BEFORE migration safety check
@@ -191,7 +197,12 @@ _tl_compute_data_root() {
   _tl_own=$(_tl_dir_under "$_tl_wt")
   if [ "$_tl_own" != "$(_tl_dir_under "$_tl_main")" ] \
     && { [ -d "$_tl_own" ] || [ -f "$_tl_own/HANDOFF.md" ]; }; then
-    printf '%s' "$_tl_wt"
+    # Canonicalized (issue #42 review finding) - same reasoning as the
+    # worktree-list-unparseable branch above: every return path in this
+    # function must agree on raw vs. canonical, or a caller comparing this
+    # value against a separately-canonicalized path (session-onboard.sh's
+    # sharing note) sees a false "different location" from a symlink alone.
+    printf '%s' "$_tl_wt_canonical"
     return
   fi
   # Return canonicalized main worktree path for data sharing

hooks/session-onboard.sh

@@ -87,7 +87,20 @@ echo
 # Make worktree-sharing (issue #31) non-silent: when this session is a linked
 # worktree and its data anchored to the main tree instead, say so plainly
 # rather than leaving it to be inferred from where HANDOFF.md happens to live.
-if [ "$droot" != "$root" ]; then
+#
+# $droot is canonicalized (see _tl_compute_data_root in _lib.sh); $root is
+# deliberately NOT (tl_root()'s own doc comment - it anchors file-path
+# relativization elsewhere in this script and must match tool input paths
+# exactly). Comparing them directly is therefore a symlink false-positive
+# waiting to happen: on any project whose raw path passes through a symlink
+# (macOS's /tmp -> /private/tmp being the everyday case), $root and $droot
+# differ even for the literal main working tree, wrongly claiming sharing on
+# every single session there. Canonicalize $root ONLY for this comparison -
+# not the variable itself - so the "is this actually a different location"
+# check compares like with like without disturbing $root's other uses below
+# (issue #42 investigation; the CI-only worktree-fixture bug it was filed
+# for was unrelated to this and is fixed separately in tests/run.sh).
+if [ "$droot" != "$(_tl_canonicalize_path "$root")" ]; then
   echo "🔗 throughline data is shared with the main working tree at \`$droot\` (this is a linked worktree)."
   echo
 fi

tests/run.sh

@@ -17,6 +17,27 @@
 # shellcheck disable=SC2016
 
 set -u
+
+# Fixtures below run `git commit` (and `git worktree add`, which needs a
+# real commit to branch from) against throwaway repos under $WORK. Git
+# refuses to commit without an author identity, and a bare CI runner has no
+# global user.email/user.name configured (actions/checkout doesn't set one
+# for the runner's global config, only for its own internal auth) — so on
+# such a runner every fixture below silently failed the commit, which
+# silently skipped worktree add (all of it chained with `&&` and swallowed
+# by `2>/dev/null`), which left every downstream worktree-detection
+# assertion resolving against a directory that was never created. That
+# looked exactly like a bug in hooks/_lib.sh's worktree logic and wasn't —
+# see dynamic/throughline#42. Setting these env vars (not global git config)
+# makes every git commit in this script self-contained regardless of the
+# ambient environment's identity config, matching how the rest of this
+# script already avoids depending on ambient state.
+GIT_AUTHOR_NAME="throughline-tests"
+GIT_AUTHOR_EMAIL="throughline-tests@localhost"
+GIT_COMMITTER_NAME="throughline-tests"
+GIT_COMMITTER_EMAIL="throughline-tests@localhost"
+export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_COMMITTER_NAME GIT_COMMITTER_EMAIL
+
 ROOT=$(unset CDPATH; cd -- "$(dirname -- "$0")/.." && pwd)
 H="$ROOT/hooks"
 PASS=0
@@ -282,7 +303,8 @@ eq "tl_data_dir honors absolute THROUGHLINE_DATA_DIR" \
 WT_MAIN="$WORK/wt-main"
 mkdir -p "$WT_MAIN"
 ( cd "$WT_MAIN" && git init -q && git commit -q --allow-empty -m init \
-    && git worktree add -q "$WORK/wt-linked" -b feat ) 2>/dev/null
+    && git worktree add -q "$WORK/wt-linked" -b feat ) 2>/dev/null \
+  || bad "fixture setup failed: wt-linked (git init/commit/worktree add)"
 WT_LINK="$WORK/wt-linked"
 D_LINK=$(CLAUDE_PROJECT_DIR="$WT_LINK" sh -c '. "'"$H"'/_lib.sh"; tl_data_dir')
 has   "linked worktree data dir points at the MAIN tree" "$D_LINK" "wt-main/.claude/throughline"
@@ -319,13 +341,28 @@ hasnt "onboard does not note sharing from the main working tree" "$O_MAIN" 'shar
 WT_OLD_MAIN="$WORK/wt-old-main"
 mkdir -p "$WT_OLD_MAIN"
 ( cd "$WT_OLD_MAIN" && git init -q && git commit -q --allow-empty -m init \
-    && git worktree add -q "$WORK/wt-old-linked" -b old ) 2>/dev/null
+    && git worktree add -q "$WORK/wt-old-linked" -b old ) 2>/dev/null \
+  || bad "fixture setup failed: wt-old-linked (git init/commit/worktree add)"
 WT_OLD_LINK="$WORK/wt-old-linked"
 mkdir -p "$WT_OLD_LINK/.claude/throughline"
 printf -- '# Test\n**Last Updated:** 2024-01-01\n' > "$WT_OLD_LINK/.claude/throughline/HANDOFF.md"
 D_OLD=$(CLAUDE_PROJECT_DIR="$WT_OLD_LINK" sh -c '. "'"$H"'/_lib.sh"; tl_data_dir')
 has "a worktree with PRE-EXISTING data keeps resolving to its own root" "$D_OLD" "wt-old-linked/.claude/throughline"
 
+# 5e6b. issue #42 review finding: onboard's sharing note must NOT fire for
+#       this worktree - it is deliberately NOT sharing (the migration guard
+#       above keeps it on its own root). _tl_compute_data_root() used to
+#       return this branch's path raw (uncanonicalized) while every other
+#       branch returned canonical, so on a symlinked $WORK (true of macOS's
+#       mktemp -d, /tmp -> /private/tmp) onboard's raw-vs-canonical
+#       comparison saw two different-looking strings for the SAME directory
+#       and wrongly printed a sharing note - the exact opposite of what this
+#       branch exists to guarantee. Both sides of that comparison are
+#       canonical now; this pins the observable (the printed message), not
+#       just the internal path value 5e6 above already checks.
+O_OLD=$(printf '%s' '{"source":"startup","session_id":"T"}' | CLAUDE_PROJECT_DIR="$WT_OLD_LINK" sh "$H/session-onboard.sh")
+hasnt "onboard does not claim sharing for a worktree keeping its own data" "$O_OLD" 'shared with the main working tree'
+
 # 5e7. once the shared main root ALSO has data (or is later adopted), sharing
 #      applies going forward - the migration guard only protects data that
 #      would otherwise be stranded, not a permanent per-worktree carve-out.
@@ -342,7 +379,8 @@ has "once main tree also has data, the worktree still keeps its own (guard is st
 WT_IGN_MAIN="$WORK/wt-ign-main"
 mkdir -p "$WT_IGN_MAIN"
 ( cd "$WT_IGN_MAIN" && git init -q && git commit -q --allow-empty -m init \
-    && git worktree add -q "$WORK/wt-ign-linked" -b ign ) 2>/dev/null
+    && git worktree add -q "$WORK/wt-ign-linked" -b ign ) 2>/dev/null \
+  || bad "fixture setup failed: wt-ign-linked (git init/commit/worktree add)"
 WT_IGN_LINK="$WORK/wt-ign-linked"
 : > "$WT_IGN_LINK/.throughlineignore"
 O_IGN=$(printf '%s' '{"source":"startup","session_id":"T"}' | CLAUDE_PROJECT_DIR="$WT_IGN_LINK" sh "$H/session-onboard.sh")