edge-case-generator·authoring·active

Edge Case Generator

Synthesizes non-obvious edge cases — Unicode, off-by-one, race conditions, replay attacks. Uses a curated catalog of past production incidents as priors.

TARAtrigger · agent

Edge Case Generator

Synthesizes non-obvious edge cases that theScenario Decomposer might miss because they don't follow from the requirement text alone — they follow from past production incidents.

When this skill fires

·AfterScenario Decomposer produces its initial set

·When the user explicitly asks TARA to "go deeper on edges"

·On regression-driven authoring (a new bug class is added to the catalog)

The catalog as priors

This skill maintains a curated catalog of edge-case patterns drawn from real production incidents. Each entry is:

·Pattern — a generalized description (e.g. "off-by-one in pagination cursor")

·Trigger condition — when this pattern is likely to apply

·Test sketch — how to exercise it

The catalog is the difference between"think harder" and"here's the specific failure mode that bit Stripe in 2019".

Pattern classes

Encoding & locale

·Unicode normalization (café vs cafe\u0301)

·Right-to-left override characters in usernames

·Surrogate pairs in length-limited fields

·Locale-specific date/number formats slipping past validation

Timing & ordering

·Off-by-one on inclusive/exclusive boundaries

·Clock skew across services

·Replay attacks within nonce windows

·Out-of-order event delivery

Concurrency

·Read-modify-write races on counters

·Double-submit on slow networks

·Lost updates from concurrent edits

·Deadlocks on cross-resource locking

Exhaustion

·Connection pool drain under sustained load

·Retry storms after a transient failure

·Memory pressure from unbounded result sets

·Quota collisions across tenants on shared infra

What it produces

For each applicable pattern, a scenario stub theGherkin Formatter can flesh out — including the trigger condition (so the test is reproducible) and the expected system behavior under that trigger.

→Edge cases that don't apply to the current requirement are silently skipped. No filler.

Example

For a login + rate-limit requirement, this skill might surface:

·Concurrent login attempts from different IPs (concurrency)

·Login attempt with Unicode-normalized email (encoding)

·Lockout boundary at exactly 5 attempts in 14:59 (off-by-one)

·Reset of failed_attempts counter after lockout expiry (timing)

Related · authoring

Requirement Parser

requirement-parser

Reads ambiguous user stories, Jira tickets, or PRDs. Extracts actors, contracts, side effects, and constraints into a normalized intent graph.

Scenario Decomposer

scenario-decomposer

Breaks a normalized requirement into happy paths, edge cases, and negative paths. Anchors edge cases on real boundaries — timing, encoding, concurrency, exhaustion.

Gherkin Formatter

gherkin-formatter

Renders scenarios as Cucumber-compliant Gherkin with realistic data. Tags scenarios with [EDGE] / [NEGATIVE] for downstream agents.