Add JSON output format for CLI commands

docs/troubleshooting.md

@@ -36,6 +36,42 @@ rg -n "backend:" <config-path>
 
 Safe fix: use `backend: local`, `backend: ssh`, or `backend: s3` for executable workflows.
 
+## `--format: format must be text or json`
+
+Likely cause: a command was run with an unsupported output format.
+
+Diagnostic:
+
+```sh
+go run ./cmd/distributor run --help
+```
+
+Safe fix: use `--format text` or `--format json`. Help and usage output are always text.
+
+## `--format json` wrote no JSON output
+
+Likely cause: the command failed before it could construct a result, such as a missing config file, invalid arguments, unreadable secrets directory, or source setup failure.
+
+Diagnostic:
+
+```sh
+go run ./cmd/distributor run --config <config-path> --format json
+```
+
+Safe fix: read the stderr error and fix the setup problem. JSON mode writes a document only after the command has enough information to construct a result.
+
+## `--format json` exited non-zero with `ok: false`
+
+Likely cause: `run` began planning or executing destinations, and at least one destination failed while other destination results were still available.
+
+Diagnostic:
+
+```sh
+go run ./cmd/distributor run --config <config-path> --format json
+```
+
+Safe fix: inspect the top-level `errors` array, `result.actions`, and `result.summary`. Fix the failed destination, then preview with `--dry-run --format json` before retrying.
+
 ## `prefix must be a clean relative slash-separated path`
 
 Likely cause: S3 `prefix` contains traversal, dot segments, empty segments, or backslashes after leading and trailing slashes are trimmed.