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[BLOCKING] Execute skill steps in declared order. NEVER skip, reorder, or merge steps without explicit user approval. [BLOCKING] Before each step or sub-skill call, update task tracking: set in_progress when step starts, set completed when step ends. [BLOCKING] Every completed/skipped step MUST include brief evidence or explicit skip reason. [BLOCKING] If Task tools are unavailable, create and maintain an equivalent step-by-step plan tracker with the same status transitions.

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Quick Summary

Goal: Produce maintainable, spec-traceable E2E tests (TC-{MODULE}-E2E-{NNN}) from recordings, specs, or code changes that protect business behavior using the project's configured framework (Playwright, Selenium, Cypress, others) — so future UI changes break tests only when intended behavior breaks.

Summary:

• Purpose: turn recordings/specs/code changes into maintainable, spec-traceable E2E tests that break ONLY when intended business behavior breaks — never on cosmetic UI churn.
• Main steps (in order): (1) detect the E2E framework from project files; (2) read docs/project-reference/e2e-test-reference.md + the e2eTesting block of docs/project-config.json FIRST — never assume a stack or invent a TC-annotation marker; (3) load TC-{MODULE}-E2E-{NNN} specs from docs/specs/; (4) pass the Real-World Fidelity Gate BEFORE writing test code — can this flow, timing, and data actually occur in production?; (5) generate/update tests via Page Object Model (spawn the e2e-runner sub-agent); (6) run tests with the project's configured command; (7) update e2e-test-reference.md with learnings.
• Every test carries its TC-{MODULE}-E2E-{NNN} code traced to the §8 invariant/behavior it guards, structured with Page Object Model (locators/actions in the page class, assertions in the test).
• Selector priority semantic/BEM > data-testid > ARIA/role > visible text; AVOID generated classes, :nth-child, XPath.
• Generate unique self-sufficient data (GUID/timestamp); NEVER depend on pre-existing DB state, NEVER tear down seeded data; pick a workflow via AskUserQuestion when not already in one.

Workflow:

1. Detect — classify request scope, target artifacts, framework.
2. Execute — apply required steps, evidence-backed actions.
3. Verify — confirm constraints, output quality, completion evidence.

Key Rules:

• MUST ATTENTION keep claims evidence-based (file:line), confidence >80% to act.
• MUST ATTENTION apply the Real-World Fidelity Gate before writing setup — a flow, pacing, or data shape production can never reach proves nothing; fix the SCENARIO, never the assertion.
• MUST ATTENTION keep task tracking updated as each step starts/completes.
• NEVER skip mandatory workflow or skill gates.

⚠️ MANDATORY: Read Project E2E Reference (FIRST)

BEFORE ANY E2E WORK, you MUST ATTENTION:

# 1. Read project-specific E2E patterns (REQUIRED)
head -100 docs/project-reference/e2e-test-reference.md

# 2. Read project config for framework, paths, commands
grep -A 50 '"e2eTesting"' docs/project-config.json

# 3. Find TC codes you need to implement
grep -r "TC-.*-E2E-" docs/specs/ docs/specs/

The e2eTesting section in docs/project-config.json contains:

• Framework, language, paths, run commands, TC code format
• Project-specific best practices and entry points

When investigating/fixing E2E failures, update docs/project-reference/e2e-test-reference.md with learnings.

• docs/project-reference/domain-entities-reference.md — Domain entity catalog, relationships, cross-service sync (read when task involves business entities/models)

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Framework Detection (SECOND STEP)

Detect the project's E2E stack before generating tests:

# Use project config, project-reference docs, and existing test config files as the source of truth
rg "playwright|cypress|selenium|webdriver|e2e" docs/project-config.json docs/project-reference/ . 2>/dev/null
rg --files | rg "(playwright|cypress|webdriver|selenium|e2e|test).*config|manifest|project"

Framework	Config Source	Test Naming	Run Command
Configured E2E framework	project config/reference docs	existing local examples	configured test command

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Workflow Modes

Mode	Input	Output
from-recording	Recording JSON + feature	Test spec + page object
update-ui	Git diff of UI changes	Updated screenshot baselines
from-changes	Changed test specs or code	Updated test implementations
from-spec	TC codes from test specs	New tests matching specs

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First Principle — Easy to Change

The success metric of every coding decision is future change cost. DRY, SRP, abstraction, design patterns, naming, layering, tests — every technique exists to serve one goal: making the next change cheaper.

Evaluating code, refactor, test, abstraction, ask: does this make next change cheaper or more expensive?

• Reject "best practices" raising change cost (premature abstraction, speculative generality, leaky indirection, ceremony without payoff).
• Name real enemies in findings: coupling, hidden state, duplicated knowledge, unclear intent, irreversible decisions exposed too early.
• Simpler design easy to change beats sophisticated design that isn't.

Apply this lens before invoking any specific rule, pattern, checklist below — if downstream rule would raise change cost, this principle wins.

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Core Principles

1. TC Code Traceability (MANDATORY)

Every E2E test MUST ATTENTION have:

• TC code in test name: TC-{MODULE}-E2E-{NNN}
• Tag/annotation linking to spec
• Comment linking to feature doc

// TypeScript
test('TC-RT-E2E-001: Submit return request', async () => { ... });

Use repository's configured test-case annotation mechanism for non-TypeScript E2E tests; NEVER invent a framework-specific marker.

Spec-Loop Discipline (E2E tier — tailored). Trace each E2E scenario to the §8 invariant/behavior it guards — name the protected business rule, not just the click path — so the scenario fails only when that intended behavior breaks (not on cosmetic UI churn). Any coverage gap you find (an §8 behavior with no E2E scenario, or an E2E flow guarding no documented behavior) feeds the Dual-Feedback half into BOTH the spec (the missing/changed behavior) AND the tests — never a test-only fix. Scoped N/A: property/metamorphic generation and the MUTATION-SCORE assertion gate are scoped to unit/integration core-logic; they do NOT apply at the E2E tier — do not force them here.

2. Page Object Model

All frameworks use Page Object pattern:

• Encapsulate page locators in page class
• Methods represent user actions
• Assertions in test file, not page object

3. Selector Strategy (Priority Order)

1. Semantic classes — BEM (.block__element), component classes
2. Data attributes — [data-testid], [data-cy], [data-test]
3. ARIA/Role — role=button, aria-label
4. Text content — Visible user text (last resort)

AVOID: Generated classes (.ng-star-inserted, .MuiButton-root), positional selectors (:nth-child), XPath

4. Unique Test Data

Tests MUST generate unique data to be repeatable:

• Append GUIDs/timestamps to test data
• Make each test self-sufficient with own generated data; NEVER depend on specific pre-existing database state
• Leave seeded data in place after run, NEVER clean up — why: teardown across shared runs creates side effects for parallel/repeat tests

5. Preconditions Documentation

Document what must exist before test runs:

• System: Infrastructure running, APIs healthy
• Data: Seed data exists (users, companies)
• Feature: Configurations complete

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Steps

1. Detect framework from project files
2. Read project E2E docs for conventions and patterns
3. Load test specs with TC codes from feature docs
4. Check real-world fidelity — BEFORE any test code is written, answer "Can this flow, timing, and data actually occur in production?" State the real pacing between consecutive user actions (a user does not submit two distinct actions in the same millisecond) and, for each gap, the observable settle signal the next step waits on (rendered confirmation, persisted state change, audit/version stamp, request/worker idle marker). Any "no" → fix the SCENARIO, never the assertion. Full contract: SYNC:real-world-fidelity-testing below.
5. Generate/update tests following Page Object pattern
6. Run tests using project's configured commands
7. Update e2e-test-reference.md with any learnings

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Output

Report:

• Files created/modified
• TC codes covered
• Run command to execute tests
• Any preconditions or setup needed

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Sub-Agent Type Override

MANDATORY: E2E test generation and baseline updates spawn e2e-runner sub-agent (subagent_type: "e2e-runner"), NOT the main agent directly. Rationale: e2e-runner auto-detects the project's E2E stack, maintains test-to-spec TC traceability, and handles visual baseline updates across Playwright, Selenium, Cypress, and other frameworks.

Spawn e2e-runner sub-agent for:

• Generating new E2E tests from recordings or TC codes from specs
• Updating visual screenshot baselines after UI changes
• Maintaining TC code traceability (TC-{MODULE}-E2E-{NNN}) in test implementations

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Workflow Recommendation

MANDATORY IMPORTANT MUST ATTENTION — NO EXCEPTIONS: If you are NOT already in a workflow, you MUST ATTENTION use AskUserQuestion to ask the user. Do NOT judge task complexity or decide this is "simple enough to skip" — the user decides whether to use a workflow, not you:

1. Activate e2e --source=changes workflow (Recommended) — scout → e2e-test → test → watzup
2. Execute /e2e-test directly — run this skill standalone

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Skill: e2e-test

Category: [Testing] Trigger: e2e test, e2e from recording, generate e2e, playwright test, cypress test, selenium test, webdriver, puppeteer

Generate and maintain E2E tests using project's configured testing framework.

• docs/specs/ — Test specifications by module (read existing TCs for E2E scenario coverage; match TC codes to E2E test implementations)

Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).

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Sub-Agent Selection — Full routing contract: .claude/skills/shared/sub-agent-selection-guide.md Rule: Route specialized domains (architecture, security, performance, DB, E2E, integration-test, git) to the matching specialist agent (see guide above) — NEVER use code-reviewer for these. — why: code-reviewer lacks each domain's checklist, so specialized issues slip through.

<!-- /SYNC:sub-agent-selection --> <!-- SYNC:source-test-drift-check -->

Source/test drift check. For coding, fix, debug, investigation, test, or review work: when source behavior changes, inspect affected unit/integration/E2E tests and decide from evidence whether tests should change to match intended behavior or the source change is an unintended bug to fix. Do not write tests for migration code; schema/data migrations are one-time execution paths, not core application logic.

<!-- /SYNC:source-test-drift-check --> <!-- SYNC:real-world-fidelity-testing -->

Real-World Fidelity Gate — MANDATORY when authoring, reviewing, or repairing any integration / E2E / system test.

A test earns trust by reproducing a situation the system can actually meet in production. A scenario that could never occur in real life proves nothing when it passes, and wastes hours when it fails.

1. Ask the fidelity question BEFORE writing the setup: "Can this sequence, timing, and data actually occur in production?" If no, the test is mis-specified — fix the SCENARIO, never the assertion.
2. Model real pacing between actor steps. Two distinct actor actions that production separates by seconds, minutes, or hours MUST NOT be fired back-to-back in the same millisecond. Compressed pacing manufactures races the system was never designed to survive, then reports them as product defects.
3. Wait on a real signal, never a blind sleep. Find an observable proving the prior step finished — a persisted state change, an audit/version stamp, a queue/worker idle marker, a completion event — and poll until it settles (unchanged across a short stability window). Use a fixed delay ONLY when no observable exists, and say so in a comment.
4. Barriers belong in ARRANGE, never in ASSERT. Waiting for a precondition is fidelity. Widening an assertion's timeout, loosening a comparison, adding a retry around a failing assertion, or skipping the test is masking. NEVER do the latter to force green.
5. Distinguish harness-amplified from real. Test topologies (shared infra, fan-out consumers, parallel suites, cold starts) can make a rare production race routine locally. Before filing a product defect, state whether the trigger exists in production and at what likelihood.
6. Keep the protected invariant intact. Improving fidelity must NEVER reduce what the test protects. If a realistic scenario no longer exercises the rule, the rule needs a DIFFERENT realistic scenario — not a weaker assertion.
7. Deliberate impossible-state tests are allowed, but MUST be labelled. Corruption-repair, migration, and fail-safe tests intentionally construct states production should never reach; comment WHY the state is reachable (upstream bug, partial write, legacy data), so they are never confused with unrealistic setups.

<!-- /SYNC:real-world-fidelity-testing --> <!-- SYNC:test-failure-fault-adjudication -->

Test-Failure Fault Adjudication — When a test fails (or you are debugging or fixing a failure), the job is to determine who is at fault — the source code or the test code. Getting that verdict right matters more than turning the suite green. Binds every debug / fix / test skill identically.

1. Provisional verdict before touching either side. Classify the observed evidence as SOURCE-WRONG, TEST-WRONG, TEST-NOT-OPTIMAL, ENVIRONMENT-BLOCKED, or AMBIGUOUS; then /debug-investigate and trace end-to-start before editing. A green-again suite is NOT the goal.
2. Triangulate against the spec AND the source. If a governing Feature Spec covers the behavior (e.g. docs/specs/** — §3 ACs / §4 BRs / §5 invariants / §8 TCs), it is the tiebreaker for intended behavior — compare BOTH the production source and the failing test against it. With no spec, the documented intent / acceptance criteria / caller contract is the reference. Decide from this evidence whether the SOURCE is wrong or the TEST is wrong.
3. Classify who is at fault, then fix the wrong side at its root:
   • SOURCE-WRONG — production code violates the spec's intended behavior or a clear invariant → fix the source at the owning layer; keep or strengthen the test that caught it.
   • TEST-WRONG — the test encodes a stale or incorrect assertion, setup, or expectation that contradicts intended behavior → fix the test at its root. NEVER weaken an assertion, add a skip, or relax a timeout to force green.
   • TEST-NOT-OPTIMAL — intended behavior is valid but the test seam, timing, or assertion signal is fragile → improve the test without weakening the invariant.
   • ENVIRONMENT-BLOCKED — infrastructure or external state prevents a source/test verdict → preserve diagnostics and stop mutation until the environment is healthy.
   • AMBIGUOUS — evidence or intended behavior does not safely select an owner → ask the user or canonical owner before editing.
   • NEVER change a test to match broken source, and NEVER change source to satisfy a broken test. (Migration code excluded — schema/data migrations are one-time execution paths, not core application logic.)
4. Ask the user when intended behavior is unclear. If no spec covers the behavior, the spec is silent, or the spec is ambiguous about which side is correct, STOP and AskUserQuestion (or consult the canonical spec owner) before editing either side — never silently pick source or test just to make the suite pass.

Reconcile to intended behavior, never to whichever side currently passes — green can encode the very bug.

<!-- /SYNC:test-failure-fault-adjudication --> <!-- SYNC:ai-mistake-prevention -->

AI Mistake Prevention — Failure modes to avoid on every task:

Re-read files after context changes. Context compaction, resume, or long-running work can make memory stale; verify current files before acting. Verify generated content against source evidence. AI hallucinates APIs, names, claims, and document facts. Check the relevant source before documenting or referencing. Check downstream references before deleting or renaming. Removing an artifact can stale docs, generated mirrors, configs, and callers; map references first. Trace the full impact chain after edits. Changing a definition can miss derived outputs and consumers. Follow the affected chain before declaring done. Verify ALL affected outputs, not just the first. One green check is not all green checks; validate every output surface the change can affect. Assume existing values are intentional — ask WHY before changing OR flagging one as a defect. Before changing or reporting a constant, limit, flag, cutoff, wording, or pattern, read nearby context and history, the CALLER's ordering, and 2+ sibling call sites of the same convention. A doc stating WHAT without WHY is missing rationale, not proof of a missing guard. Surface ambiguity before acting — don't pick silently. Multiple valid interpretations require an explicit question or stated assumption with risk. Assert the outcome your system owns, not the intermediate state your infrastructure owns. When verifying async work, assert the final business state — never the delivery/retry bookkeeping held in shared infrastructure that any co-running process can write. Such a check passes when run alone and flakes the moment anything else shares that infrastructure. Keep shared guidance role-relevant. Universal guidance must help every receiving skill or agent; code-specific obligations belong only in code-specific protocols.

<!-- /SYNC:ai-mistake-prevention --> <!-- SYNC:critical-thinking-mindset -->

Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.

<!-- /SYNC:critical-thinking-mindset --> <!-- SYNC:critical-thinking-mindset:reminder -->

MUST ATTENTION apply critical + sequential thinking — every claim needs appropriate traced evidence (file:line for repo/code claims; source URL or artifact section for research, product, content, and docs claims); confidence >80% to act, <60% DO NOT recommend. Anti-hallucination: never present guess as fact, admit uncertainty freely, cross-reference independently, stay skeptical of own confidence.

<!-- /SYNC:critical-thinking-mindset:reminder --> <!-- SYNC:ai-mistake-prevention:reminder -->

MUST ATTENTION apply AI mistake prevention — verify generated content against evidence, trace downstream references before deleting or renaming, verify all affected outputs, re-read files after context loss, and surface ambiguity before acting.

<!-- /SYNC:ai-mistake-prevention:reminder --> <!-- PROMPT-ENHANCE:STEP-TASK-CLOSING:START -->

Prompt-Enhance Closing Anchors

IMPORTANT MUST ATTENTION follow declared step order for this skill; NEVER skip, reorder, or merge steps without explicit user approval IMPORTANT MUST ATTENTION for every step/sub-skill call: set in_progress before execution, set completed after execution IMPORTANT MUST ATTENTION every skipped step MUST include explicit reason; every completed step MUST include concise evidence IMPORTANT MUST ATTENTION if Task tools unavailable, maintain an equivalent step-by-step plan tracker with synchronized statuses

<!-- PROMPT-ENHANCE:STEP-TASK-CLOSING:END --> <!-- SYNC:parallel-subagent-dispatch -->

Parallel Sub-Agent Dispatch — Plan parallelism the moment a task breakdown exists, BEFORE executing it — running provably independent tasks sequentially wastes wall-clock. Applies to every multi-step job: workflow steps, planning, batch updates, investigation, research, scans, reviews, doc sync. Plan execution is metadata-gated, NEVER default-parallel — fan-out follows ONLY what the plan declares (PAR/SEQ tags + per-phase write set); an untagged plan runs sequentially — why: a derived write set cannot see cascade or generated writes.

1. Tag every task PAR or SEQ. PAR = inputs exclude every pending task's output AND write set disjoint from every other PAR. Else SEQ — MUST ATTENTION name the dependency forcing it.
2. Group PAR into waves. No edge between members. Two writers of one file NEVER share a wave. Read-only work (search, investigation, review, research) parallelizes freely.
3. Declare before dispatch: Parallel plan: wave 1 = [...] · wave 2 = [...] · SEQ = [...] (reason).
4. Spawn each wave in ONE message — every Agent call in one response, NEVER dripped per turn. Route each task to its specialist (.claude/skills/shared/sub-agent-selection-guide.md); NEVER code-reviewer as catch-all.
5. Brief each sub-agent self-contained: goal · scope + owned files · reference docs · return contract (summary + Full report: path, per SYNC:subagent-return-contract) · incremental persistence to plans/reports/ (per SYNC:incremental-persistence).
6. Barrier per wave. Advance ONLY after EVERY member returns (a skipped conditional counts as returned). Merge, mark each task completed/skipped, THEN dispatch the next wave. Mutating steps wait for the barrier.
7. One level deep. A dispatched sub-agent executes its own brief; further fan-out stays the orchestrator's job unless that agent's .claude/agents/*.md definition authorizes it.

NEVER parallelize: tasks sharing a write target · a task consuming a pending task's output · trivial single-file work (dispatch overhead > gain) · an order a skill or workflow explicitly fixes · gates awaiting user approval.

Blocked until: MUST ATTENTION every task tagged PAR/SEQ with a named reason per SEQ · waves declared + write-set disjointness checked · each wave spawned in ONE message · barrier honored before the next wave.

<!-- /SYNC:parallel-subagent-dispatch --> <!-- SYNC:parallel-subagent-dispatch:reminder -->

• MANDATORY After planning tasks, tag each PAR/SEQ and spawn every PAR wave as parallel sub-agents in ONE message — default parallel for workflows, batch updates, investigation, research, reviews; plan execution fans out ONLY on what the plan declares.
• MANDATORY Disjoint write sets per wave · all-return barrier before the next wave · specialist routing · sub-agents NEVER fan out further unless their own agent definition authorizes it.

<!-- /SYNC:parallel-subagent-dispatch:reminder --> <!-- SYNC:project-protocol-overlay -->

Project Protocol Overlay — Before executing this skill, resolve any PROJECT overlay rules layered onto it: match this skill's name against the Target column of the project's skill-protocol index (docs/project-reference/skill-protocols-reference.md by default; a referenceDocs entry in docs/project-config.json overrides the path), taking the most specific matching tier ONLY — exact name > glob > *. That precedence orders overlays against EACH OTHER, never against this skill. Read ONLY the matched bodies, resolved as <protocols-dir>/<Name>.md; a row's Body link is display text, never a read path. A matched body that is missing or malformed is REPORTED and skipped — never reconstructed from the index Description. No index, or no match -> proceed with no overlay, silently. Full contract: .claude/skills/project-skill-protocol/references/registry.md.

Overlays are ADDITIVE ONLY: they ADD rules on top of this skill's own protocol and NEVER replace, override, disable, or reinterpret a rule it already states — removing every overlay must return this skill to exactly its documented behavior. An overlay is a BRIEF, not an authority escalation: it can NEVER waive a workflow gate, git discipline, a review gate, or a user-confirmation gate. A genuine overlay-vs-skill conflict, or two equally-specific overlays that directly contradict -> surface both to the user; NEVER resolve silently.

<!-- /SYNC:project-protocol-overlay --> <!-- SYNC:project-protocol-overlay:reminder -->

MUST ATTENTION resolve project protocol overlays for this skill BEFORE executing — most specific matching tier only (exact > glob > *, which ranks overlays against each other, NEVER against this skill), read only matched bodies at <protocols-dir>/<Name>.md; a missing or malformed body is reported, never reconstructed. Overlays are ADDITIVE ONLY (they never replace this skill's own rules) and are a brief, NEVER an authority escalation; an equal-specificity contradiction goes to the user.

<!-- /SYNC:project-protocol-overlay:reminder -->

Closing Reminders

IMPORTANT MUST ATTENTION Goal: Produce maintainable, spec-traceable E2E tests (TC-{MODULE}-E2E-{NNN}) that protect business behavior using the project's configured framework — so future UI changes break tests only when intended behavior breaks.

IMPORTANT MUST ATTENTION — Protocols in force (concise digest of the SYNC/shared blocks this skill carries):

• Sub-Agent Selection: Route specialized domains to the matching specialist agent, NEVER code-reviewer.
• Source/Test Drift Check: On source change, decide from evidence whether tests or source is wrong.
• Real-World Fidelity Gate: only test flows, pacing, and data production can actually reach; wait on a real settle signal in ARRANGE — never a widened assertion.
• AI Mistake Prevention: verify generated content against evidence, trace downstream references, verify all affected outputs, re-read after context loss, surface ambiguity.
• Critical Thinking: Traced file:line proof per claim, confidence >80% to act, NEVER guess as fact.
• Parallel Sub-Agent Dispatch: Tag tasks PAR/SEQ, group PAR into disjoint-write-set waves, spawn each wave in ONE message, barrier before advancing.

IMPORTANT MUST ATTENTION — Main steps (execute in order, track each): (1) detect E2E framework from project files; (2) read e2e-test-reference.md + e2eTesting config FIRST; (3) load TC-{MODULE}-E2E-{NNN} specs from docs/specs/; (4) pass the Real-World Fidelity Gate BEFORE writing test code; (5) generate/update tests via Page Object Model through the e2e-runner sub-agent; (6) run tests with the configured command; (7) update e2e-test-reference.md with learnings — why: AI keeps dropping the skill's own step sequence under long context. IMPORTANT MUST ATTENTION read docs/project-reference/e2e-test-reference.md + the e2eTesting block of docs/project-config.json FIRST, then detect the framework from project files — NEVER assume a stack — why: the configured framework, paths, run commands, and TC format are project-specific, not framework defaults. IMPORTANT MUST ATTENTION cite file:line evidence for every claim (confidence >80% to act, <60% DO NOT recommend) — NEVER speculate without proof. MANDATORY IMPORTANT MUST ATTENTION break work into small todo tasks using TaskCreate BEFORE starting; mark one in_progress, set completed immediately after each finishes; add a final review todo. MANDATORY IMPORTANT MUST ATTENTION search the codebase for 3+ similar existing E2E tests/page objects before creating new code; follow the local pattern over generic framework docs — why: projects carry local selector/data conventions that differ from defaults. IMPORTANT MUST ATTENTION evaluate fit before copying a nearby test — verify the new scenario shares the same base page class, fixtures, and preconditions — why: closest example ≠ matching preconditions. MANDATORY IMPORTANT MUST ATTENTION every E2E test carries its TC-{MODULE}-E2E-{NNN} code traced to the §8 invariant/behavior it guards — name the protected business rule, not just the click path — so it fails on intended-behavior breaks, not cosmetic UI churn. MANDATORY IMPORTANT MUST ATTENTION apply the Real-World Fidelity Gate BEFORE writing setup — ask "can this flow, timing, and data actually occur in production?", model real pacing between distinct user actions instead of firing them in the same millisecond, and wait on an observable settle signal in ARRANGE; NEVER widen an assertion timeout, loosen a comparison, or retry around a failing assertion to compensate — why: a scenario production can never reach proves nothing when it passes and manufactures phantom "product defects" when it fails. IMPORTANT MUST ATTENTION use the repository's configured test-case annotation mechanism — NEVER invent a framework-specific marker. MANDATORY IMPORTANT MUST ATTENTION selector priority semantic/BEM > data-testid > ARIA/role > visible text; NEVER use generated classes (.ng-star-inserted, .MuiButton-root), positional selectors (:nth-child), or XPath — why: generated/positional selectors break on unrelated markup churn. MANDATORY IMPORTANT MUST ATTENTION keep locators/actions in the Page Object class, assertions in the test file — why: encapsulation keeps the next UI change a one-place edit. MANDATORY IMPORTANT MUST ATTENTION generate unique self-sufficient data (GUID/timestamp); NEVER depend on specific pre-existing DB state and NEVER tear down seeded data — why: teardown across shared/parallel runs creates side effects. IMPORTANT MUST ATTENTION spawn the e2e-runner sub-agent (subagent_type: "e2e-runner") for E2E generation and visual baseline updates — NEVER drive them from the main agent — why: e2e-runner carries the stack auto-detection and TC-traceability knowledge. IMPORTANT MUST ATTENTION any coverage gap (a §8 behavior with no scenario, or a flow guarding no documented behavior) feeds BOTH the spec AND the tests — NEVER a test-only fix; property/metamorphic generation and MUTATION-SCORE gates are scoped to unit/integration, N/A at the E2E tier. IMPORTANT MUST ATTENTION update docs/project-reference/e2e-test-reference.md with learnings when investigating/fixing E2E failures. MANDATORY IMPORTANT MUST ATTENTION add a final review todo task to verify work quality.

Anti-Rationalization:

Evasion	Rebuttal
"I know the framework, skip the reference"	Read e2eTesting config + reference FIRST — stack/paths/TC format are project-specific.
"data-testid is everywhere, just use it"	Honor the priority — semantic/BEM > data-testid > ARIA > text; show the selector you rejected.
"This selector is faster via :nth-child"	Positional/generated selectors break on unrelated churn. Use a semantic/data anchor.
"I'll clean up the data after the run"	NEVER tear down seeded data — teardown breaks parallel/repeat runs. Leave it in place.
"Test passes, traceability is bookkeeping"	No TC code traced to a §8 behavior = no bug protection. Name the rule the scenario guards.
"Just generate the test inline, it's quick"	Spawn e2e-runner — it owns stack detection, TC traceability, and baseline updates.

Closing reminder — Easy to Change is the success metric. Every finding, test, refactor, and abstraction must answer one question: does this make the next change cheaper or more expensive? If it doesn't reduce future change cost, reject it. Coupling, hidden state, duplicated knowledge, and unclear intent are the real enemies — call them out by name.

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IMPORTANT MUST ATTENTION read e2eTesting config + e2e-test-reference.md FIRST and detect the framework — NEVER assume a stack. IMPORTANT MUST ATTENTION every test carries its TC-{MODULE}-E2E-{NNN} code traced to the §8 behavior it guards; selector priority semantic > data-attr > ARIA > text — NEVER generated/positional/XPath. IMPORTANT MUST ATTENTION generate unique self-sufficient data, NEVER tear down seeded data; spawn e2e-runner for generation and baseline updates.