feat: Support machine-readable JSON help flag output

.changes/unreleased/added-20261026-103451.yaml

@@ -0,0 +1,6 @@
+kind: added
+body: Add machine-readable JSON help for root, group, and leaf commands with offline help discovery and a versioned schema
+time: 2026-10-26T10:34:51.302706323Z
+custom:
+    Author: aviatco
+    AuthorLink: https://github.com/aviatco

docs/essentials/output_format.md

@@ -72,6 +72,62 @@ The configuration is stored in your Fabric CLI configuration file and applies to
 
 ## JSON Output Schema
 
+### help in JSON format
+
+Use JSON help to discover commands, arguments, and flags for scripts and automation.
+
+```bash
+# Root help
+fab --help --output_format json
+
+# Command help
+fab mkdir -h --output_format json
+
+# Subcommand help
+fab job run --help --output_format json
+
+# Equivalent shorthand
+fab job run --help --json
+
+# Help accepts combined short flags
+fab ls -lh --output_format json
+```
+
+In interactive mode, omit the `fab` prefix:
+
+```text
+help --output_format json
+help --output_format text
+```
+
+JSON help follows this response structure. Array contents depend on the selected
+command; root help lists available commands and global flags.
+
+```json
+{
+    "timestamp": "<UTC timestamp>",
+    "status": "Success",
+    "command": "<canonical command name>",
+    "result": {
+        "data": [
+            {
+                "schema_version": "1.0",
+                "cli_version": "<installed CLI version>",
+                "description": "<command description>",
+                "usage": "fab <command> [flags]",
+                "args": [],
+                "flags": [],
+                "aliases": [],
+                "subcommands": [],
+                "examples": [],
+                "notes": [],
+                "learn_more": []
+            }
+        ]
+    }
+}
+```
+
 ### Success Response Structure
 ```json
 {

docs/essentials/parameters.md

@@ -14,6 +14,16 @@ For command-specific parameters:
 fab <command> --help
 ```
 
+For machine-readable help, add `--output_format json`:
+
+```bash
+fab job run --help --output_format json
+```
+
+`--help`, `-h`, and `-help` support JSON and text. See
+[Json format help](output_format.md#help-in-json-format) for the response
+contract, format precedence, and offline behavior.
+
 For a complete list of commands, see the [Commands page](../commands/index.md).
 
 
@@ -61,6 +71,7 @@ For a complete list of commands, see the [Commands page](../commands/index.md).
 | `--interval`       | Specify the interval for `job` schedule                 |
 | `--json`           | Use JSON output (same as `--output_format json`)         |
 | `--mode`           | Specify the operational mode for `table load`           |
+| `--output_format`  | Select `json` or `text` for results and help             |
 | `--retain_n_hours` | Retain specified hours for `table vacuum`               |
 | `--schedule`       | Set the job schedule for `job`                          |
 | `--show_headers`   | Turn headers on for `api`                               |