SW-216 — Reject duplicate keys in stellarforge.config.json #398

Summary

JSON.parse silently accepts duplicate object keys and keeps the last value. A project config containing duplicate network, identity, or version keys can therefore be interpreted ambiguously by tools that use different parsing rules. Reject duplicate keys before validating the configuration object.

Workstream

• Workstream: WS-CONFIG
• Primary scope: src/config/project.ts; src/config/schema.ts; tests/config-malformed-json.test.ts
• Protected surface: Yes — maintainer review required
• Priority: P1
• Difficulty: high
• Proposed points: 200

Acceptance Criteria

• Duplicate keys at the top level are detected and rejected.
• Duplicate keys nested in unsupported values are rejected consistently or explicitly documented as out of scope.
• No network or identity value is selected from an ambiguous document.
• Error output identifies the duplicate key without echoing its value.
• Existing valid config files remain compatible.

Dependencies

None.

Out of Scope

• Unrelated architecture or public command-contract changes.
• New runtime dependencies without maintainer approval.
• Mainnet deployment or remote template execution.

Definition of Done

• Acceptance criteria have deterministic regression coverage.
• Security and compatibility boundaries remain intact.
• Supported-platform CI passes.

Labels

• Stellar Wave (do not apply until activation is explicitly authorized)
• type: security
• area: config
• priority: P1
• difficulty: high
• points: 200
• workstream: config

Sequencing and scope note

Related existing scope: #340 covers static config-file permissions and symlink policy; this issue is specifically duplicate JSON property detection.