feat(sdd): plan-scoped workspace — one .superpowers/sdd/<plan> dir per plan

sdd-workspace now requires the plan file and resolves
.superpowers/sdd/<plan-basename>/; task-brief and review-package write
into their plan's directory (review-package gains PLAN_FILE as its first
argument). Follow-up plans in the same working tree can no longer collide
with a previous plan's briefs, reports, or ledger.

skills/subagent-driven-development/scripts/review-package

@@ -4,26 +4,28 @@
 # call. Using the recorded per-task BASE (not HEAD~1) keeps multi-commit
 # tasks intact.
 #
-# Usage: review-package BASE HEAD [OUTFILE]
-# Default OUTFILE: <repo-root>/.superpowers/sdd/review-<base7>..<head7>.diff
+# Usage: review-package PLAN_FILE BASE HEAD [OUTFILE]
+# Default OUTFILE: <repo-root>/.superpowers/sdd/<plan-basename>/review-<base7>..<head7>.diff
 # (named per range, so a re-review after fixes gets a distinct fresh file).
 set -euo pipefail
 
-if [ $# -lt 2 ] || [ $# -gt 3 ]; then
-  echo "usage: review-package BASE HEAD [OUTFILE]" >&2
+if [ $# -lt 3 ] || [ $# -gt 4 ]; then
+  echo "usage: review-package PLAN_FILE BASE HEAD [OUTFILE]" >&2
   exit 2
 fi
 
-base=$1
-head=$2
+plan=$1
+base=$2
+head=$3
+[ -f "$plan" ] || { echo "no such plan file: $plan" >&2; exit 2; }
 
 git rev-parse --verify --quiet "$base" >/dev/null || { echo "bad BASE: $base" >&2; exit 2; }
 git rev-parse --verify --quiet "$head" >/dev/null || { echo "bad HEAD: $head" >&2; exit 2; }
 
-if [ $# -eq 3 ]; then
-  out=$3
+if [ $# -eq 4 ]; then
+  out=$4
 else
-  dir=$("$(cd "$(dirname "$0")" && pwd)/sdd-workspace")
+  dir=$("$(cd "$(dirname "$0")" && pwd)/sdd-workspace" "$plan")
   out="$dir/review-$(git rev-parse --short "$base")..$(git rev-parse --short "$head").diff"
 fi
 

skills/subagent-driven-development/scripts/sdd-workspace

@@ -1,22 +1,40 @@
 #!/usr/bin/env bash
-# Resolve and ensure the working-tree directory SDD uses for its short-lived
-# artifacts: task briefs, implementer reports, review packages, and the
-# progress ledger. Print the directory's absolute path.
+# Resolve and ensure the working-tree directory SDD uses for one plan's
+# short-lived artifacts: task briefs, implementer reports, review packages,
+# and the progress ledger. Print the plan directory's absolute path.
+#
+# One directory per plan (.superpowers/sdd/<plan-basename>/) so a follow-up
+# plan in the same working tree can never read or overwrite another plan's
+# artifacts. A stale ledger misread as current progress makes controllers
+# skip whole task sequences — plan-scoping removes that failure structurally.
 #
 # The workspace lives in the working tree (not under .git/) because Claude Code
 # treats .git/ as a protected path and denies agent writes there — which blocks
 # an implementer subagent from writing its report file. A self-ignoring
-# .gitignore keeps the workspace out of `git status` and out of accidental
-# commits without modifying any tracked file.
+# .gitignore at .superpowers/sdd/ keeps every plan's workspace out of
+# `git status` and out of accidental commits without modifying any tracked file.
 #
 # Single source of truth for the workspace location, so task-brief and
 # review-package cannot drift to different directories.
 #
-# Usage: sdd-workspace
+# Usage: sdd-workspace PLAN_FILE
 set -euo pipefail
 
+if [ $# -ne 1 ]; then
+  echo "usage: sdd-workspace PLAN_FILE" >&2
+  exit 2
+fi
+
+plan=$1
+[ -f "$plan" ] || { echo "no such plan file: $plan" >&2; exit 2; }
+
+slug=$(basename "$plan" .md)
+[ -n "$slug" ] && [ "$slug" != "." ] && [ "$slug" != ".." ] \
+  || { echo "cannot derive a workspace name from: $plan" >&2; exit 2; }
+
 root=$(git rev-parse --show-toplevel)
-dir="$root/.superpowers/sdd"
+base="$root/.superpowers/sdd"
+dir="$base/$slug"
 mkdir -p "$dir"
-printf '*\n' > "$dir/.gitignore"
+printf '*\n' > "$base/.gitignore"
 cd "$dir" && pwd

skills/subagent-driven-development/scripts/task-brief

@@ -4,8 +4,9 @@
 # through the controller's context.
 #
 # Usage: task-brief PLAN_FILE TASK_NUMBER [OUTFILE]
-# Default OUTFILE: <repo-root>/.superpowers/sdd/task-<N>-brief.md
-# (per worktree; concurrent runs in the same working tree share it).
+# Default OUTFILE: <repo-root>/.superpowers/sdd/<plan-basename>/task-<N>-brief.md
+# (per plan and per worktree; concurrent runs of the SAME plan in the same
+# working tree share it).
 set -euo pipefail
 
 if [ $# -lt 2 ] || [ $# -gt 3 ]; then
@@ -20,7 +21,7 @@ n=$2
 if [ $# -eq 3 ]; then
   out=$3
 else
-  dir=$("$(cd "$(dirname "$0")" && pwd)/sdd-workspace")
+  dir=$("$(cd "$(dirname "$0")" && pwd)/sdd-workspace" "$plan")
   out="$dir/task-${n}-brief.md"
 fi