garrytan · tongchen92 · Apr 30, 2026
diff --git a/AGENTS.md b/AGENTS.md
@@ -11,6 +11,7 @@ Skills live in `.agents/skills/`. Invoke them by name (e.g., `/office-hours`).
 | Skill | What it does |
 |-------|-------------|
 | `/office-hours` | Start here. Reframes your product idea before you write code. |
+| `/product-iteration` | Existing-product iteration: turn usage, feedback, and surprise behavior into the next move. |
 | `/plan-ceo-review` | CEO-level review: find the 10-star product in the request. |
 | `/plan-eng-review` | Lock architecture, data flow, edge cases, and tests. |
 | `/plan-design-review` | Rate each design dimension 0-10, explain what a 10 looks like. |

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,49 @@
 # Changelog
 
+## [1.21.0.0] - 2026-04-29
+
+## **Existing products now get their own strategy loop.**
+## **You can iterate from signal, not founder taste alone.**
+
+If you already have users, `/office-hours` is no longer the only thoughtful starting point. gstack now ships `/product-iteration`, a new skill built for the moment after reality has spoken: users are doing something interesting, support keeps hearing the same complaint, activation is soft, or the product is being bent into a workflow you did not plan for. Instead of brainstorming from vibes, it starts from observed behavior, separates facts from interpretation, forces a normalized decision metric, classifies the problem into one primary iteration mode, and ends with 3 distinct directions plus a concrete 7-day test.
+
+This fills a real gap in the stack. `/office-hours` is still the greenfield move. `/plan-ceo-review` is still the ambition check. `/product-iteration` now sits between them for existing products that need evidence-driven next moves. The routing docs, install docs, and generated skill catalog all point to it, so the workflow is discoverable instead of living as tribal knowledge.
+
+### The numbers that matter
+
+Source: `product-iteration/SKILL.md.tmpl`, `README.md`, `docs/skills.md`, and `SKILL.md.tmpl` in this branch. Reproduce with repo-local inspection and `rg product-iteration README.md docs/skills.md SKILL.md.tmpl`.
+
+| Surface | Before | After | Δ |
+|---|---:|---:|---:|
+| Existing-product iteration skills in gstack | 0 | 1 | +1 |
+| Explicit iteration modes in the workflow | 0 | 5 | +5 |
+| Forcing questions aimed at real product signal | 0 | 6 | +6 |
+| Required strategic options per run | 0 | 3 | +3 |
+| Default experiment horizon in the output | 0 days | 7 days | +7 days |
+
+The big shift is not the file count. It is that gstack now has a first-class answer for "what should we build next?" when the right answer depends on evidence, not taste. That makes the product loop tighter for teams that already shipped and now need judgment, not just ideation.
+
+For founders and product builders, use `/product-iteration` the first time you have real behavior, real complaints, or real pull. It should sharpen scope before you widen it, and it should stop a lot of premature platform thinking. Try it when you catch yourself saying "users keep doing this weird thing" or "we have feedback, but I don't know what it means yet."
+
+### Itemized changes
+
+#### Added
+
+- `/product-iteration`, a new existing-product strategy skill focused on real usage, feedback, retention, activation, workflow expansion, monetization, and wedge decisions.
+- A structured iteration brief that separates observed facts, interpretations, open questions, and evidence quality before making recommendations.
+- A decision frame that requires a normalized metric, denominator, baseline, meaningful lift target, three distinct options, and a recommended 7-day test.
+
+#### Changed
+
+- Root skill routing now sends existing-product "what should we build next?" asks to `/product-iteration` instead of overloading `/office-hours` or `/plan-ceo-review`.
+- `README.md`, `docs/skills.md`, `AGENTS.md`, and `CLAUDE.md` now document where `/product-iteration` fits in the gstack workflow.
+- Generated skill docs now include `/product-iteration` across supported hosts.
+
+#### For contributors
+
+- `product-iteration/SKILL.md.tmpl` is the source of truth. Regenerate with `bun run gen:skill-docs` or `bun run build` after edits.
+- Contributed by @tongchen92.
+
 ## [1.20.0.0] - 2026-04-28
 
 ## **Browser-skills land. `/scrape <intent>` first call drives the page; second call runs the codified script in 200ms.**

diff --git a/CLAUDE.md b/CLAUDE.md
@@ -119,6 +119,7 @@ gstack/
 ├── codex/           # /codex skill (multi-AI second opinion via OpenAI Codex CLI)
 ├── land-and-deploy/ # /land-and-deploy skill (merge → deploy → canary verify)
 ├── office-hours/    # /office-hours skill (YC Office Hours — startup diagnostic + builder brainstorm)
+├── product-iteration/ # /product-iteration skill (existing-product iteration from real usage + feedback)
 ├── investigate/     # /investigate skill (systematic root-cause debugging)
 ├── retro/           # Retrospective skill (includes /retro global cross-project mode)
 ├── bin/             # CLI utilities (gstack-repo-mode, gstack-slug, gstack-config, etc.)

diff --git a/README.md b/README.md
@@ -35,10 +35,11 @@ Fork it. Improve it. Make it yours. And if you want to hate on free open source
 
 1. Install gstack (30 seconds — see below)
 2. Run `/office-hours` — describe what you're building
-3. Run `/plan-ceo-review` on any feature idea
-4. Run `/review` on any branch with changes
-5. Run `/qa` on your staging URL
-6. Stop there. You'll know if this is for you.
+3. If you already have users, run `/product-iteration` on real feedback or usage
+4. Run `/plan-ceo-review` on any feature idea
+5. Run `/review` on any branch with changes
+6. Run `/qa` on your staging URL
+7. Stop there. You'll know if this is for you.
 
 ## Install — 30 seconds
 
@@ -48,7 +49,7 @@ Fork it. Improve it. Make it yours. And if you want to hate on free open source
 
 Open Claude Code and paste this. Claude does the rest.
 
-> Install gstack: run **`git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/.claude/skills/gstack && cd ~/.claude/skills/gstack && ./setup`** then add a "gstack" section to CLAUDE.md that says to use the /browse skill from gstack for all web browsing, never use mcp\_\_claude-in-chrome\_\_\* tools, and lists the available skills: /office-hours, /plan-ceo-review, /plan-eng-review, /plan-design-review, /design-consultation, /design-shotgun, /design-html, /review, /ship, /land-and-deploy, /canary, /benchmark, /browse, /connect-chrome, /qa, /qa-only, /design-review, /setup-browser-cookies, /setup-deploy, /setup-gbrain, /retro, /investigate, /document-release, /codex, /cso, /autoplan, /plan-devex-review, /devex-review, /careful, /freeze, /guard, /unfreeze, /gstack-upgrade, /learn. Then ask the user if they also want to add gstack to the current project so teammates get it.
+> Install gstack: run **`git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/.claude/skills/gstack && cd ~/.claude/skills/gstack && ./setup`** then add a "gstack" section to CLAUDE.md that says to use the /browse skill from gstack for all web browsing, never use mcp\_\_claude-in-chrome\_\_\* tools, and lists the available skills: /office-hours, /product-iteration, /plan-ceo-review, /plan-eng-review, /plan-design-review, /design-consultation, /design-shotgun, /design-html, /review, /ship, /land-and-deploy, /canary, /benchmark, /browse, /connect-chrome, /qa, /qa-only, /design-review, /setup-browser-cookies, /setup-deploy, /setup-gbrain, /retro, /investigate, /document-release, /codex, /cso, /autoplan, /plan-devex-review, /devex-review, /careful, /freeze, /guard, /unfreeze, /gstack-upgrade, /learn. Then ask the user if they also want to add gstack to the current project so teammates get it.
 
 ### Step 2: Team mode — auto-update for shared repos (recommended)
 
@@ -179,6 +180,7 @@ Each skill feeds into the next. `/office-hours` writes a design doc that `/plan-
 | Skill | Your specialist | What they do |
 |-------|----------------|--------------|
 | `/office-hours` | **YC Office Hours** | Start here. Six forcing questions that reframe your product before you write code. Pushes back on your framing, challenges premises, generates implementation alternatives. Design doc feeds into every downstream skill. |
+| `/product-iteration` | **Existing-Product PM** | Turn real usage, feedback, and surprise behavior into a sharp next move. Finds the strongest pull, generates 3 ambitious directions, and recommends a 7-day test. |
 | `/plan-ceo-review` | **CEO / Founder** | Rethink the problem. Find the 10-star product hiding inside the request. Four modes: Expansion, Selective Expansion, Hold Scope, Reduction. |
 | `/plan-eng-review` | **Eng Manager** | Lock in architecture, data flow, diagrams, edge cases, and tests. Forces hidden assumptions into the open. |
 | `/plan-design-review` | **Senior Designer** | Rates each design dimension 0-10, explains what a 10 looks like, then edits the plan to get there. AI Slop detection. Interactive — one AskUserQuestion per design choice. |
@@ -451,7 +453,7 @@ Data is stored in [Supabase](https://supabase.com) (open source Firebase alterna
 ```
 ## gstack
 Use /browse from gstack for all web browsing. Never use mcp__claude-in-chrome__* tools.
-Available skills: /office-hours, /plan-ceo-review, /plan-eng-review, /plan-design-review,
+Available skills: /office-hours, /product-iteration, /plan-ceo-review, /plan-eng-review, /plan-design-review,
 /design-consultation, /design-shotgun, /design-html, /review, /ship, /land-and-deploy,
 /canary, /benchmark, /browse, /open-gstack-browser, /qa, /qa-only, /design-review,
 /setup-browser-cookies, /setup-deploy, /setup-gbrain, /retro, /investigate, /document-release,

diff --git a/SKILL.md b/SKILL.md
@@ -436,6 +436,7 @@ quality gates that produce better results than answering inline.
 
 **Routing rules — when you see these patterns, INVOKE the skill via the Skill tool:**
 - User describes a new idea, asks "is this worth building", brainstorms, pitches a concept → invoke `/office-hours`
+- User has an existing product and asks what to build next based on users, feedback, activation, retention, or surprising usage → invoke `/product-iteration`
 - User asks about strategy, scope, ambition, "think bigger", "what should we build" → invoke `/plan-ceo-review`
 - User asks to review architecture, lock in the plan, "does this design make sense" → invoke `/plan-eng-review`
 - User asks about design system, brand, visual identity, "how should this look" → invoke `/design-consultation`

diff --git a/SKILL.md.tmpl b/SKILL.md.tmpl
@@ -32,6 +32,7 @@ quality gates that produce better results than answering inline.
 
 **Routing rules — when you see these patterns, INVOKE the skill via the Skill tool:**
 - User describes a new idea, asks "is this worth building", brainstorms, pitches a concept → invoke `/office-hours`
+- User has an existing product and asks what to build next based on users, feedback, activation, retention, or surprising usage → invoke `/product-iteration`
 - User asks about strategy, scope, ambition, "think bigger", "what should we build" → invoke `/plan-ceo-review`
 - User asks to review architecture, lock in the plan, "does this design make sense" → invoke `/plan-eng-review`
 - User asks about design system, brand, visual identity, "how should this look" → invoke `/design-consultation`

diff --git a/VERSION b/VERSION
@@ -1 +1 @@
-1.20.0.0
+1.21.0.0
diff --git a/docs/skills.md b/docs/skills.md
@@ -5,6 +5,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | Skill | Your specialist | What they do |
 |-------|----------------|--------------|
 | [`/office-hours`](#office-hours) | **YC Office Hours** | Start here. Six forcing questions that reframe your product before you write code. Pushes back on your framing, challenges premises, generates implementation alternatives. Design doc feeds into every downstream skill. |
+| [`/product-iteration`](#product-iteration) | **Existing-Product PM** | Turn real usage, feedback, and surprise behavior into a sharp next move. Finds the strongest pull, generates 3 ambitious directions, and recommends a 7-day test. |
 | [`/plan-ceo-review`](#plan-ceo-review) | **CEO / Founder** | Rethink the problem. Find the 10-star product hiding inside the request. Four modes: Expansion, Selective Expansion, Hold Scope, Reduction. |
 | [`/plan-eng-review`](#plan-eng-review) | **Eng Manager** | Lock in architecture, data flow, diagrams, edge cases, and tests. Forces hidden assumptions into the open. |
 | [`/plan-design-review`](#plan-design-review) | **Senior Designer** | Interactive plan-mode design review. Rates each dimension 0-10, explains what a 10 looks like, fixes the plan. Works in plan mode. |
@@ -99,6 +100,60 @@ After the design doc is approved, `/office-hours` reflects on what it noticed ab
 
 ---
 
+## `/product-iteration`
+
+This is the skill for **what to build next after reality has spoken**.
+
+`/office-hours` is for before the product exists. `/product-iteration` is for after users have done something interesting, annoying, or revealing enough that your next move should be anchored in evidence, not taste alone.
+
+### What it does
+
+It starts from actual product signal:
+
+- user behavior
+- retention or activation patterns
+- support complaints
+- surprise workflows
+- repeated feature requests
+- manual workarounds
+
+Then it forces the core product questions:
+
+- Where is the pull most concentrated?
+- What are users still doing outside the product?
+- What surprised you in real usage?
+- What pain shows up when the product fails or disappears?
+- Which repeated request is actually a deeper job?
+- If you believe the strongest signal, what bigger product becomes obvious?
+
+### Why this matters
+
+Most iteration advice is too mushy. It averages across users too early, overweights what people say instead of what they do, and jumps from one quote to a giant platform vision. This skill is stricter.
+
+It forces:
+
+- one primary mode: activation, retention, workflow expansion, monetization, or wedge
+- a normalized decision metric with a denominator
+- evidence-quality grading
+- three meaningfully different options
+- a concrete 7-day test with kill criteria
+
+The result is a product iteration brief that says, clearly: **this is the strongest signal, this is the bigger job trying to emerge, this is the direction to test next**.
+
+### When to use it
+
+Use `/product-iteration` when you say things like:
+
+- "What should we build next?"
+- "Here’s what users are telling us."
+- "Where should we double down?"
+- "Help me analyze this feedback dump."
+- "Activation is weak — what does the evidence say?"
+
+If there is no real user or product signal yet, use `/office-hours` instead.
+
+---
+
 ## `/plan-ceo-review`
 
 This is my **founder mode**.

diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.20.0.0",
+  "version": "1.21.0.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",