# Feature Specification: Scripting Stdout Interception

**Feature Branch**: `043-stdout-interception`  
**Created**: 2026-06-18  
**Status**: Draft  
**Input**: User description: "issue #127"

## User Scenarios & Testing *(mandatory)*

### User Story 1 - Rhai Script Output Capture (Priority: P1)

As a database developer writing Rhai scripts, I want my script's `print()` statements to be captured and appended to the execution logs, so that I can debug my scripts effectively during execution.

**Why this priority**: Rhai is the default scripting backend. Debugging scripts without print output is difficult and hinders development.

**Independent Test**: Can be fully tested by integration tests executing a script with `print("hello")` and asserting the resulting execution context contains "hello" in its stdout buffer.

**Acceptance Scenarios**:

1. **Given** a Rhai script execution context, **When** the script `print("hello");` is executed, **Then** the string "hello" is captured in the execution output logs.
2. **Given** a Rhai script execution context, **When** multiple `print()` statements are executed, **Then** all printed strings are captured sequentially.

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### User Story 2 - PL/SQL Output Capture (Priority: P1)

As a database user writing PL/SQL procedures, I want to use `PRINT` or `RAISE NOTICE` to output messages so that I can trace execution flow and debug my procedures.

**Why this priority**: PL/SQL is heavily used for database procedures; lack of debugging output prevents effective script development.

**Independent Test**: Can be fully tested by parsing and executing PL/SQL blocks containing `PRINT` and `RAISE NOTICE`, and checking the resulting execution context logs.

**Acceptance Scenarios**:

1. **Given** a PL/SQL execution context, **When** the statement `PRINT 'hello';` is executed, **Then** the evaluated string "hello" is captured in the execution output logs.
2. **Given** a PL/SQL execution context, **When** the statement `RAISE NOTICE 'hello';` is executed, **Then** the evaluated string "hello" is captured in the execution output logs.
3. **Given** a PL/SQL statement with an expression like `PRINT 1 + 2;`, **When** executed, **Then** the expression is evaluated to "3" and captured in the logs.

### Edge Cases

- What happens when a script prints a very large string or prints within an infinite loop? (Memory limits on the output buffer)
- How are null values or unprintable types handled by `PRINT` or `RAISE NOTICE`?
- What happens if `PRINT` is called with an expression that fails evaluation at runtime?

## Requirements *(mandatory)*

### Functional Requirements

- **FR-001**: The system MUST intercept native print calls in the Rhai engine and forward the output to the execution context's standard output buffer.
- **FR-002**: The system MUST support parsing `PRINT expression;` as a valid PL/SQL statement.
- **FR-003**: The system MUST support parsing `RAISE NOTICE expression;` as a valid PL/SQL statement.
- **FR-004**: The system MUST evaluate expressions provided to `PRINT` or `RAISE NOTICE` at runtime.
- **FR-005**: The system MUST append the evaluated string representation from PL/SQL print statements to the execution context's standard output buffer.
- **FR-006**: Existing stdout capture functionality for other languages (e.g., Python) MUST NOT be affected.

### Key Entities

- **Print Statement Node**: The logical representation of a print or notice command in the PL/SQL parser.
- **Execution Context**: The state object responsible for collecting and storing script output during execution.

## Success Criteria *(mandatory)*

### Measurable Outcomes

- **SC-001**: 100% of captured output correctly matches the printed values and evaluation results from the scripts.
- **SC-002**: Automated tests verify stdout capture for both Rhai and PL/SQL under varying input conditions.
- **SC-003**: Code coverage does not drop below the current minimum threshold.
- **SC-004**: The codebase passes all project-specific linting and formatting rules without warnings.

## Assumptions

- The execution context's output buffer is already designed to be thread-safe and capable of storing standard output messages.
- The `PRINT` and `RAISE NOTICE` PL/SQL syntax is intended to process a single expression rather than a comma-separated list of arguments.