merge: origin/main v1.0.0.0 into garrytan/fix-checkpoints

Main shipped the v1 prompts rewrite (simpler writing style + real LOC
receipts + /plan-tune observational substrate). Resolved conflicts:

- VERSION / package.json: bumped 0.18.5.0 → 1.0.1.0 (main is 1.0.0.0,
  this branch lands next).
- CHANGELOG: moved the /context-save + /context-restore entry to the
  top as v1.0.1.0, above main's v1.0.0.0. Also removed the em-dash
  variants in the new entry (ship voice rule).
- TODOS: kept both sections — Context skills (lane feature TODO) first,
  main's PACING_UPDATES_V0 + Plan Tune v2 deferrals below.
- Migration: renamed gstack-upgrade/migrations/v0.18.5.0.sh →
  v1.0.1.0.sh (matches new version). Test path updated.

preamble.ts auto-merged cleanly: main's question-tuning, explain_level,
and writing-style sections composed with my context-save/context-restore
routing rule.

All SKILL.md files regenerated via `bun run gen:skill-docs --host all`
per CLAUDE.md's "never resolve generated files by accepting either
side" rule. Golden fixtures (claude/codex/factory ship) also regenerated.

bun test: 0 failures.

gstack-upgrade/migrations/v1.0.0.0.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+# Migration: v1.0.0.0 — V1 writing style prompt
+#
+# What changed: tier-≥2 skills default to ELI10 writing style (jargon glossed on
+# first use, outcome-framed questions, short sentences). Power users who prefer
+# the older V0 prose can set `gstack-config set explain_level terse`.
+#
+# What this does: writes a "pending prompt" flag file. On the first tier-≥2 skill
+# invocation after upgrade, the preamble reads the flag and asks the user once
+# whether to keep the new default or opt into terse mode. Flag file is deleted
+# after the user answers. Idempotent — safe to run multiple times.
+#
+# Affected: every user on v0.19.x and below who upgrades to v1.x
+set -euo pipefail
+
+GSTACK_HOME="${GSTACK_HOME:-$HOME/.gstack}"
+PROMPTED_FLAG="$GSTACK_HOME/.writing-style-prompted"
+PENDING_FLAG="$GSTACK_HOME/.writing-style-prompt-pending"
+
+mkdir -p "$GSTACK_HOME"
+
+# If the user has already answered the prompt at any point, skip.
+if [ -f "$PROMPTED_FLAG" ]; then
+  exit 0
+fi
+
+# If the user has already explicitly set explain_level (either way), count that
+# as an answer — they've made their choice, don't ask again.
+EXPLAIN_LEVEL_SET="$("${HOME}/.claude/skills/gstack/bin/gstack-config" get explain_level 2>/dev/null || true)"
+if [ -n "$EXPLAIN_LEVEL_SET" ]; then
+  touch "$PROMPTED_FLAG"
+  exit 0
+fi
+
+# Write the pending flag — preamble will see it on the first tier-≥2 skill invocation.
+touch "$PENDING_FLAG"
+
+echo "  [v1.0.0.0] V1 writing style: you'll see a one-time prompt on your next skill run asking if you want the new default (glossed jargon, outcome framing) or the older terse prose."

gstack-upgrade/migrations/v1.0.1.0.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Migration: v0.18.5.0 — Remove stale /checkpoint skill installs
+# Migration: v1.0.1.0 — Remove stale /checkpoint skill installs
 #
 # Claude Code ships /checkpoint as a native alias for /rewind, which was
 # shadowing the gstack checkpoint skill. The skill has been split into
@@ -66,10 +66,10 @@ if [ -L "$OLD_TOPLEVEL" ]; then
   target_real=$(resolve_real "$OLD_TOPLEVEL")
   if [ -n "$GSTACK_ROOT_REAL" ] && path_inside "$target_real" "$GSTACK_ROOT_REAL"; then
     rm "$OLD_TOPLEVEL"
-    echo "  [v0.18.5.0] Removed stale /checkpoint symlink (was shadowing Claude Code's /rewind alias)."
+    echo "  [v1.0.1.0] Removed stale /checkpoint symlink (was shadowing Claude Code's /rewind alias)."
     removed_any=1
   else
-    echo "  [v0.18.5.0] Leaving $OLD_TOPLEVEL alone — symlink target is outside gstack."
+    echo "  [v1.0.1.0] Leaving $OLD_TOPLEVEL alone — symlink target is outside gstack."
   fi
 elif [ -d "$OLD_TOPLEVEL" ]; then
   # Regular directory. Only remove if it contains exactly one file named
@@ -79,13 +79,13 @@ elif [ -d "$OLD_TOPLEVEL" ]; then
     target_real=$(resolve_real "$OLD_TOPLEVEL/SKILL.md")
     if [ -n "$GSTACK_ROOT_REAL" ] && path_inside "$target_real" "$GSTACK_ROOT_REAL"; then
       rm -r "$OLD_TOPLEVEL"
-      echo "  [v0.18.5.0] Removed stale /checkpoint install directory (gstack prefix-mode)."
+      echo "  [v1.0.1.0] Removed stale /checkpoint install directory (gstack prefix-mode)."
       removed_any=1
     else
-      echo "  [v0.18.5.0] Leaving $OLD_TOPLEVEL alone — SKILL.md symlink target is outside gstack."
+      echo "  [v1.0.1.0] Leaving $OLD_TOPLEVEL alone — SKILL.md symlink target is outside gstack."
     fi
   else
-    echo "  [v0.18.5.0] Leaving $OLD_TOPLEVEL alone — not a gstack-owned install (has custom content)."
+    echo "  [v1.0.1.0] Leaving $OLD_TOPLEVEL alone — not a gstack-owned install (has custom content)."
   fi
 fi
 # Missing → no-op (idempotency).
@@ -93,12 +93,12 @@ fi
 # --- Shape 2: ~/.claude/skills/gstack/checkpoint/  (gstack owns this dir unconditionally)
 if [ -d "$OLD_NAMESPACED" ] || [ -L "$OLD_NAMESPACED" ]; then
   rm -rf "$OLD_NAMESPACED"
-  echo "  [v0.18.5.0] Removed stale ~/.claude/skills/gstack/checkpoint/ (replaced by context-save + context-restore)."
+  echo "  [v1.0.1.0] Removed stale ~/.claude/skills/gstack/checkpoint/ (replaced by context-save + context-restore)."
   removed_any=1
 fi
 
 if [ "$removed_any" = "1" ]; then
-  echo "  [v0.18.5.0] /checkpoint is now Claude Code's native /rewind alias. Use /context-save to save state and /context-restore to resume."
+  echo "  [v1.0.1.0] /checkpoint is now Claude Code's native /rewind alias. Use /context-save to save state and /context-restore to resume."
 fi
 
 exit 0