[IDE integrations] Add non-mutating zed inspect --format json diagnostics contract #191

Goal

Add a stable, credential-free, non-mutating diagnostics endpoint for editor integrations, beginning with the planned zed-pkg/zed-sublimetext plugin and reusable by VS Code, IntelliJ, JetBrains Air, and other IDE clients.

Proposed command:

zed inspect --format json --root /absolute/project/root

Required behavior

• stdout contains exactly one UTF-8 JSON document; logs/progress go to stderr;
• no project mutation, package downloads, registry contact, credential loading, or build-hook execution by default;
• inspect .zpkg.toml, .zpkg.lock, configured [install].dir, transaction recovery state, local store references, workspace members, adapter outputs, and frozen-install readiness;
• include stable diagnostic codes, severity, message/detail, precise locations, and declarative recommended actions;
• actions use argv arrays, never shell strings, and declare mutates_project, requires_network, and executes_package_code;
• absolute or explicitly rooted paths only;
• redact secrets from both streams;
• additive schema evolution within a major version and explicit schema_version.

Proposed response shape

{
  "schema_version": "1.0",
  "root": "/work/project",
  "package": {
    "manifest": "/work/project/.zpkg.toml",
    "lockfile": "/work/project/.zpkg.lock",
    "materialization_dir": "/work/project/zed_modules"
  },
  "summary": {
    "health": "warning",
    "errors": 0,
    "warnings": 1
  },
  "diagnostics": [
    {
      "code": "LOCK_STALE",
      "severity": "warning",
      "message": "Manifest intent is newer than the lockfile",
      "location": {"path": "/work/project/.zpkg.toml", "line": 12, "column": 1},
      "actions": [
        {
          "id": "refresh-lock",
          "title": "Refresh the lockfile",
          "kind": "zed-command",
          "argv": ["zed", "install"],
          "mutates_project": true,
          "requires_network": true,
          "executes_package_code": false
        }
      ]
    }
  ]
}

Acceptance criteria

• Pure inspection is deterministic and does not mutate filesystem state.
• Offline inspection succeeds for all local checks.
• Malformed manifest/lock data returns structured diagnostics rather than unstructured panics.
• The command distinguishes the zed-pkg CLI from the Zed editor launcher in integration tests.
• Linux, macOS, and Windows paths are covered.
• JSON-schema fixtures and compatibility tests are committed.
• An editor can render all recommendations without parsing human CLI output.
• No recommendation is automatically executed by the CLI.

Initial editor fallback

Until this lands, zed-sublimetext can provide a deterministic local subset: manifest/lock/materialization relationships, generated-consumer identity review, interrupted transaction detection, and zed --version/--help executable validation. The IDE should continue to confirmation-gate every mutating action even after this endpoint ships.