## ADDED Requirements

### Requirement: Structural divergence triggers a new version
The system SHALL compare a newly synthesized flow's tool-name step sequence against the currently-stored version of the matching skill, and SHALL create a new version (rather than overwriting the stored one) whenever the tool-name sequence differs by insertion, deletion, or reordering of a step.

#### Scenario: Extra step triggers a new version
- **WHEN** a newly executed flow for a matching skill contains an additional tap step not present in the currently-stored version's sequence
- **THEN** the system stores a new version of the skill rather than overwriting the existing stored version

#### Scenario: Reordered steps trigger a new version
- **WHEN** a newly executed flow for a matching skill executes the same tool names as the stored version but in a different order
- **THEN** the system stores a new version of the skill

#### Scenario: Argument-value-only differences do not trigger a version bump
- **WHEN** a newly executed flow has the identical tool-name sequence as the stored version and differs only in argument values already covered by parameter abstraction
- **THEN** the system does not create a new version, and instead updates the existing version's parameters per the skill-authoring capability

### Requirement: Version history is retained, never silently overwritten
The system SHALL retain every version of a skill it creates, each carrying an incrementing `version` number and a reference to the version it diverged from, and SHALL NOT delete or overwrite a prior version's stored record when a new version is created.

#### Scenario: New version references its parent
- **WHEN** a new version of a skill is created due to structural divergence
- **THEN** the new version's record stores a reference to the prior version's id and an incremented version number

#### Scenario: Prior version remains fetchable
- **WHEN** a new version of a skill has been created
- **THEN** the prior version's record remains retrievable by its own id, unmodified

### Requirement: Default retrieval surfaces the newest version
The system SHALL treat the highest-numbered version of a skill as the default result returned by a lookup-by-name/goal-family query, while still allowing an explicit lookup of any specific prior version by its id.

#### Scenario: Lookup by name returns newest version
- **WHEN** a caller looks up a skill by its name or goal-family without specifying a version
- **THEN** the system returns the highest-numbered stored version of that skill

#### Scenario: Explicit id lookup returns the requested version
- **WHEN** a caller requests a skill by a specific prior version's id
- **THEN** the system returns that exact version's record, not the newest version