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### Skills Library
**Testing**
+- **agentic-end-to-end-testing** - Prove a running app works through its real interface, with evidence that can't be faked
- **test-driven-development** - RED-GREEN-REFACTOR cycle (includes testing anti-patterns reference)
**Debugging**
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+---
+name: agentic-end-to-end-testing
+description: Use when verifying a running application end-to-end through its real interface (web UI, CLI/TUI, or desktop app), when asked to prove a feature works with evidence — "test it end to end", "prove it actually works", "make me a movie showing it off" — or after a change touches a user-facing surface that unit tests can't cover. Not for unit tests, code review, or API-only checks.
+---
+
+# Agentic End-to-End Testing
+
+## Overview
+
+Write a durable, falsifiable scenario; have an agent drive the live application through its real interface the way a user would; end with evidence that cannot be faked. The unit of work is a **scenario card** — a short markdown test written for an agent to execute, high-level enough that a small UI shuffle doesn't invalidate it, precise enough that two agents running it reach the same verdict. The run's product is a per-assertion pass/fail report backed by that evidence.
+
+Two disciplines govern everything here. **Unfakeable evidence:** choose evidence a model cannot fabricate — a movie whose frames you extract and look at, an HTTP 401 that proves the server actually answered, a live third-party round-trip, a hash-sealed bundle. **Honest failure:** when the interface or evidence path breaks, report it, escalate, or pivot. NEVER weaken, skip, or reinterpret an assertion to make it pass.
+
+## When to Use
+
+- A feature touches a user-facing surface (button, palette command, status indicator, keybinding, rendered message) and you want proof it works live.
+- The user asks to "test it end to end", "prove it actually works", or wants a demo they can watch.
+- You changed a layer (projection, capability gate, renderer) whose effect is only observable in the assembled application.
+
+A green unit test proves the wiring in isolation. A scenario proves the wiring *as assembled and rendered*. They catch different bugs — write the card even when the unit tests pass.
+
+Don't use this for logic with no user-facing surface (unit-test that), or when a production gate makes the live path unreachable (see the over-specification trap below).
+
+## The Scenario Card
+
+One card = one `.md` file in `test/scenarios/`. Keep these sections; collapse any to one line when the scenario is simple. Don't pad.
+
+```markdown
+# -: one-line title
+
+**What this covers**: the feature + the specific commits/IDs it exercises.
+If something else breaks this, it should be caught here.
+
+## Pre-state
+What must be true before starting: a freshly built instance running, auth/creds
+in place, a clean workdir. Give the exact commands to reach it.
+
+## Steps
+Numbered actions described by **intent**, each with the concrete command or
+tool call and a real UI label (prefer labels the user sees over brittle
+selectors like `#nav > li:nth-child(3)`).
+
+## Expected
+For each step, what you should observe — and the **falsification condition**:
+"if you see X instead, the test fails." Silence is not success.
+
+## Cleanup
+Idempotent teardown so reruns are hermetic. Never touch state you didn't create.
+
+## Sharp edges
+Footguns, timing/ordering caveats, nondeterminism noted while recording.
+```
+
+## The Run Loop
+
+1. **Preflight.** Build fresh from the code under test — the most common mistake is testing a stale binary. Rebuild every layer your change touches and confirm the running instance is the new one, not a process someone left up yesterday. Isolate hermetically: give the test instance its own HOME, port, and state directory so it can neither collide with nor pollute a real instance. Check credentials and models are in place. Run a minimal smoke check first — one where even a `401` is informative, because it means the server answered.
+2. **Write or select the card.** New behavior gets a new card; a regression check reuses an existing one.
+3. **Dispatch a disposable runner subagent** using [runner-prompt.md](runner-prompt.md). This is the default: a fresh context has no sunk-cost incentive to fudge the verdict. Running a card yourself in-session is the exception, reserved for a quick single-card check.
+4. **Capture evidence** (see Pick Your Evidence below).
+5. **Verify the evidence itself.** Extract a frame from the movie and read it. Re-read the capture file. Cross-check every rendered claim against on-disk ground truth — the UI can lie or lag; the log, database, or file is authoritative. Evidence you didn't inspect is evidence you don't have.
+6. **Clean up, idempotently.** Shut down what you spawned, remove scratch dirs, leave pre-existing instances running and untouched. Never touch state you didn't create.
+7. **Report per-assertion pass/fail with the concrete observation** — the rendered text, the on-disk value, the exit code. A vague "looks fine" is a failed report.
+
+## Pick Your Interface
+
+| Surface | Recipe |
+| --- | --- |
+| Web UI (browser) | [driving-web-browser.md](driving-web-browser.md) |
+| CLI / TUI (terminal) | [driving-cli-tui.md](driving-cli-tui.md) |
+| Desktop app | [driving-computer-use.md](driving-computer-use.md) |
+
+## Pick Your Evidence
+
+Ask one question: **what would be impossible to fabricate here?** Then capture that.
+
+| Evidence | When to choose it |
+| --- | --- |
+| Captured real output / screenshot bundle | The cheap default: a terminal transcript or screenshots of the actual run, saved to files. |
+| HTTP status / live third-party round-trip | When the claim is "the other end answered" — a real status code or a real external service response proves it. |
+| Recorded movie | When the user wants to *watch* it work. See [recording-a-proof-movie.md](recording-a-proof-movie.md). |
+| Rendered captioned demo | When the deliverable is a narrated showcase built from verified stills. See [rendering-a-demo-movie.md](rendering-a-demo-movie.md). |
+| Hash-sealed bundle | When the artifact must not drift from the log it documents — seal both together. |
+
+## Hard-Won Principles
+
+- **Falsification, always.** Every assertion states what failure looks like. A step that can't fail proves nothing — make sure your check would fire on the failure path, not just the happy path.
+- **Verify the right surface.** The same concept often exists at several layers: an internal capability vs. its REST projection, a model field vs. the rendered chip. Confirm your assertion reads the surface that carries the signal — a "missing" value is often present one layer over.
+- **Present but not visible ≠ absent.** Scrollable bodies, virtualized lists, and auto-scroll-to-bottom routinely push a real element out of the capture window. Scroll or expand to where it should be before concluding it didn't render; confirm via a sibling read of the same state.
+- **Executing the card tests the card.** Expect to find bugs in your own scenario — a wrong selector, a wrong layer, a vacuous assertion. Fix the card as you go; a card that passes because its check was vacuous is worse than none.
+- **The over-specification trap.** A card can describe a path that production gating prevents (a keybind that's a no-op in the current mode). Confirm the gate in the source rather than fighting it through the UI; verify the underlying behavior with a unit test and note the gate in the card.
+- **Cleanup is part of the test.** A half-shutdown fleet makes the next run's polling return false positives. Make teardown idempotent and scoped to what you created.
+
+## Common Rationalizations
+
+| Excuse | Reality |
+| --- | --- |
+| "The unit tests pass, so it works" | Unit tests prove the wiring in isolation; the bug class this skill exists for lives in the assembly. |
+| "I read the code; the feature is clearly correct" | Reading is not running. Drive the real interface or report that you didn't. |
+| "Screen recording is blocked, I'll ship what I have" | A blank or fabricated artifact is worse than none; pivot to evidence from the real run and say what you did. |
+| "The assertion is too strict, I'll adjust it" | NEVER weaken, skip, or reinterpret an assertion to make it pass. |
+| "I proved the backend, so the feature works" | Different claim. Say exactly what you exercised, then drive the real interface — or state that you didn't. |
+| "My check passed" | A check that would also pass with the feature broken proves nothing — a broken detector and a clean run are indistinguishable. |
+
+## Integration
+
+- Runs after superpowers:subagent-driven-development completes a feature, and before superpowers:finishing-a-development-branch decides how the work lands.
+- Complements superpowers:verification-before-completion: that skill gates any success claim on having run the checks; this one defines what counts as proof when the behavior under test is user-facing.