Add what-was-i-doing skill

Reconstruct past activity from an artifact's mtime: day-in-repos.sh
lists one day's commits and reflog entries (pulls, checkouts, clones:
local events git log never shows) across every repo locate knows.

Generated-by: Claude Opus 5.5

what-was-i-doing/day-in-repos.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+# List git activity on one day across every repo `locate` knows about.
+#
+# Usage: day-in-repos.sh YYYY-MM-DD [git-log-args...]
+#
+# Prints commits (by committer date) and reflog entries (pulls, checkouts,
+# amends: local-only events that `git log` never shows), sorted by local
+# time. A commit present in several clones/worktrees is printed once, with
+# every repo it appears in. Extra args go to `git log`, e.g. --author=dckc
+# to drop bot and upstream commits.
+set -euo pipefail
+
+[[ $# -ge 1 && $1 =~ ^[0-9]{4}-[0-9]{2}-[0-9]{2}$ ]] || {
+  sed -n '2,10p' "$0"
+  exit 2
+}
+day=$1
+shift
+next=$(date -d "$day + 1 day" +%F)
+
+locate -r '/\.git$' \
+  | grep "^$HOME/" \
+  | grep -v -e /node_modules/ -e /.cache/ -e /.cargo/ -e /go/pkg/ \
+  | while read -r g; do
+      r=${g%/.git}
+      name=${r#"$HOME"/}
+      git -C "$r" log --all --since="$day 00:00" --until="$next 00:00" \
+        --date=format:%H:%M --format="%cd	%h	$name	%s" "$@" 2>/dev/null || true
+      git -C "$r" reflog --all --date=format:'%F %H:%M' \
+        --format="%gd	$name	%gs" 2>/dev/null \
+        | awk -F'\t' -v day="$day" '
+            match($1, /\{[0-9-]+ [0-9:]+\}/) {
+              ts = substr($1, RSTART + 1, RLENGTH - 2)
+              if (substr(ts, 1, 10) == day)
+                printf "%s\treflog\t%s\t%s\n", substr(ts, 12), $2, $3
+            }' || true
+    done \
+  | awk -F'\t' '
+      # group by time+hash (reflog rows by time+subject)
+      { key = ($2 == "reflog") ? $1 FS $4 : $1 FS $2
+        if (!(key in repos)) { order[++n] = key; line[key] = $0 }
+        if (!((key, $3) in seen)) {
+          seen[key, $3] = 1
+          repos[key] = repos[key] (repos[key] ? " " : "") $3
+        } }
+      END {
+        for (i = 1; i <= n; i++) {
+          split(line[order[i]], f, FS)
+          printf "%s %-7s %s  [%s]\n", f[1], f[2], f[4], repos[order[i]]
+        }
+      }' \
+  | sort