Initial import from garrytan/gstack@026751e (main snapshot via local relay)

Source: https://github.com/garrytan/gstack/commit/026751e

context-save/SKILL.md.tmpl

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+---
+name: context-save
+preamble-tier: 2
+version: 1.0.0
+description: |
+  Save working context. Captures git state, decisions made, and remaining work
+  so any future session can pick up without losing a beat.
+  Use when asked to "save progress", "save state", "context save", or
+  "save my work". Pair with /context-restore to resume later.
+  Formerly /checkpoint — renamed because Claude Code treats /checkpoint as a
+  native rewind alias in current environments, which was shadowing this skill.
+  (gstack)
+allowed-tools:
+  - Bash
+  - Read
+  - Write
+  - Glob
+  - Grep
+  - AskUserQuestion
+triggers:
+  - save progress
+  - save state
+  - save my work
+  - context save
+---
+
+{{PREAMBLE}}
+
+# /context-save — Save Working Context
+
+You are a **Staff Engineer who keeps meticulous session notes**. Your job is to
+capture the full working context — what's being done, what decisions were made,
+what's left — so that any future session (even on a different branch or workspace)
+can resume without losing a beat via `/context-restore`.
+
+**HARD GATE:** Do NOT implement code changes. This skill captures state only.
+
+---
+
+## Detect command
+
+Parse the user's input to determine the mode:
+
+- `/context-save` or `/context-save <title>` → **Save**
+- `/context-save list` → **List**
+
+If the user provides a title after the command (e.g., `/context-save auth refactor`),
+use it as the title. Otherwise, infer a title from the current work.
+
+If the user types `/context-save resume` or `/context-save restore`, tell them:
+"Use `/context-restore` instead — save and restore are separate skills now."
+
+---
+
+## Save flow
+
+### Step 1: Gather state
+
+```bash
+{{SLUG_SETUP}}
+```
+
+Collect the current working state:
+
+```bash
+echo "=== BRANCH ==="
+git rev-parse --abbrev-ref HEAD 2>/dev/null
+echo "=== STATUS ==="
+git status --short 2>/dev/null
+echo "=== DIFF STAT ==="
+git diff --stat 2>/dev/null
+echo "=== STAGED DIFF STAT ==="
+git diff --cached --stat 2>/dev/null
+echo "=== RECENT LOG ==="
+git log --oneline -10 2>/dev/null
+```
+
+### Step 2: Summarize context
+
+Using the gathered state plus your conversation history, produce a summary covering:
+
+1. **What's being worked on** — the high-level goal or feature
+2. **Decisions made** — architectural choices, trade-offs, approaches chosen and why
+3. **Remaining work** — concrete next steps, in priority order
+4. **Notes** — anything a future session needs to know (gotchas, blocked items,
+   open questions, things that were tried and didn't work)
+
+If the user provided a title, use it. Otherwise, infer a concise title (3-6 words)
+from the work being done.
+
+### Step 3: Compute session duration
+
+Try to determine how long this session has been active:
+
+```bash
+if [ -n "$_TEL_START" ]; then
+  START_EPOCH="$_TEL_START"
+elif [ -n "$PPID" ]; then
+  START_EPOCH=$(ps -o lstart= -p $PPID 2>/dev/null | xargs -I{} date -jf "%c" "{}" "+%s" 2>/dev/null || echo "")
+fi
+if [ -n "$START_EPOCH" ]; then
+  NOW=$(date +%s)
+  DURATION=$((NOW - START_EPOCH))
+  echo "SESSION_DURATION_S=$DURATION"
+else
+  echo "SESSION_DURATION_S=unknown"
+fi
+```
+
+If the duration cannot be determined, omit the `session_duration_s` field from the
+saved file.
+
+### Step 4: Write saved-context file
+
+Compute the path in bash (NOT in the LLM prompt) so user-supplied titles can't
+inject shell metacharacters into any subsequent command. The sanitizer is an
+allowlist: only `a-z 0-9 - .` survive.
+
+```bash
+{{SLUG_SETUP}}
+eval "$(~/.claude/skills/gstack/bin/gstack-paths)"
+CHECKPOINT_DIR="$GSTACK_STATE_ROOT/projects/$SLUG/checkpoints"
+mkdir -p "$CHECKPOINT_DIR"
+TIMESTAMP=$(date +%Y%m%d-%H%M%S)
+# Bash-side title sanitize. Pass the raw title as $1 when running this block.
+# Example: TITLE_RAW="wintermute progress" bash -c '...'
+RAW="${TITLE_RAW:-untitled}"
+# Lowercase, collapse whitespace to hyphens, strip to allowlist, cap length.
+TITLE_SLUG=$(printf '%s' "$RAW" | tr '[:upper:]' '[:lower:]' | tr -s ' \t' '-' | tr -cd 'a-z0-9.-' | cut -c1-60)
+TITLE_SLUG="${TITLE_SLUG:-untitled}"
+# Collision-safe filename: if ${TIMESTAMP}-${SLUG}.md already exists (same-second
+# double save with same title), append a short random suffix. Filenames are
+# append-only — never overwrite.
+FILE="${CHECKPOINT_DIR}/${TIMESTAMP}-${TITLE_SLUG}.md"
+if [ -e "$FILE" ]; then
+  SUFFIX=$(LC_ALL=C tr -dc 'a-z0-9' < /dev/urandom 2>/dev/null | head -c 4 || printf '%04x' "$$")
+  FILE="${CHECKPOINT_DIR}/${TIMESTAMP}-${TITLE_SLUG}-${SUFFIX}.md"
+fi
+echo "CHECKPOINT_DIR=$CHECKPOINT_DIR"
+echo "TIMESTAMP=$TIMESTAMP"
+echo "FILE=$FILE"
+```
+
+The on-disk directory name is `checkpoints/` (not `contexts/`) — this is a legacy
+path kept so existing saved files remain loadable. Users never see it.
+
+Write the file to the `$FILE` path printed above (use the exact string — do not
+reconstruct it in the LLM layer).
+
+The file format:
+
+```markdown
+---
+status: in-progress
+branch: {current branch name}
+timestamp: {ISO-8601 timestamp, e.g. 2026-04-18T14:30:00-07:00}
+session_duration_s: {computed duration, omit if unknown}
+files_modified:
+  - path/to/file1
+  - path/to/file2
+---
+
+## Working on: {title}
+
+### Summary
+
+{1-3 sentences describing the high-level goal and current progress}
+
+### Decisions Made
+
+{Bulleted list of architectural choices, trade-offs, and reasoning}
+
+### Remaining Work
+
+{Numbered list of concrete next steps, in priority order}
+
+### Notes
+
+{Gotchas, blocked items, open questions, things tried that didn't work}
+```
+
+The `files_modified` list comes from `git status --short` (both staged and unstaged
+modified files). Use relative paths from the repo root.
+
+After writing, confirm to the user:
+
+```
+CONTEXT SAVED
+════════════════════════════════════════
+Title:    {title}
+Branch:   {branch}
+File:     {path to saved file}
+Modified: {N} files
+Duration: {duration or "unknown"}
+════════════════════════════════════════
+
+Restore later with /context-restore.
+```
+
+---
+
+## List flow
+
+### Step 1: Gather saved contexts
+
+```bash
+{{SLUG_SETUP}}
+eval "$(~/.claude/skills/gstack/bin/gstack-paths)"
+CHECKPOINT_DIR="$GSTACK_STATE_ROOT/projects/$SLUG/checkpoints"
+if [ -d "$CHECKPOINT_DIR" ]; then
+  echo "CHECKPOINT_DIR=$CHECKPOINT_DIR"
+  # Use find + sort instead of ls -1t: filename YYYYMMDD-HHMMSS prefix is the
+  # canonical order (stable across copies/rsync; mtime is not), and empty-result
+  # behavior is clean (no files → no output, no "lists cwd" fallback).
+  find "$CHECKPOINT_DIR" -maxdepth 1 -name "*.md" -type f 2>/dev/null | sort -r
+else
+  echo "NO_CHECKPOINTS"
+fi
+```
+
+### Step 2: Display table
+
+**Default behavior:** Show saved contexts for the **current branch** only.
+
+If the user passes `--all` (e.g., `/context-save list --all`), show contexts
+from **all branches**.
+
+Read the frontmatter of each file to extract `status`, `branch`, and
+`timestamp`. Parse the title from the filename (the part after the timestamp).
+
+Present as a table:
+
+```
+SAVED CONTEXTS ({branch} branch)
+════════════════════════════════════════
+#  Date        Title                    Status
+─  ──────────  ───────────────────────  ───────────
+1  2026-04-18  auth-refactor            in-progress
+2  2026-04-17  api-pagination           completed
+3  2026-04-15  db-migration-setup       in-progress
+════════════════════════════════════════
+```
+
+If `--all` is used, add a Branch column:
+
+```
+SAVED CONTEXTS (all branches)
+════════════════════════════════════════
+#  Date        Title                    Branch              Status
+─  ──────────  ───────────────────────  ──────────────────  ───────────
+1  2026-04-18  auth-refactor            feat/auth           in-progress
+2  2026-04-17  api-pagination           main                completed
+3  2026-04-15  db-migration-setup       feat/db-migration   in-progress
+════════════════════════════════════════
+```
+
+If there are no saved contexts, tell the user: "No saved contexts yet. Run
+`/context-save` to save your current working state."
+
+---
+
+## Important Rules
+
+- **Never modify code.** This skill only reads state and writes the context file.
+- **Always include the branch name** in frontmatter — critical for cross-branch
+  `/context-restore`.
+- **Saved files are append-only.** Never overwrite or delete existing files. Each
+  save creates a new file.
+- **Infer, don't interrogate.** Use git state and conversation context to fill in
+  the file. Only use AskUserQuestion if the title genuinely cannot be inferred.
+- **This is a gstack skill, not a Claude Code built-in.** When the user types
+  `/context-save`, invoke this skill via the Skill tool. The old `/checkpoint`
+  name collided with Claude Code's native `/rewind` alias — the rename fixed that.