syn version

The syn CLI ships to npm and the server is deployed separately, so the two can drift apart. syn version reports both sides, and every command that talks to the API checks the same thing before it runs. Commands that never call the Syntropic API skip the check: syn config, and the marketplace commands, which may still fetch marketplace registries over the network.

Output

syn version

Line 1 is always the CLI. Line 2 is the server build that answered at the configured API URL (SYN_API_URL). Against a server on the same release line:

Syntropic137 v0.33.0-beta.1
syn-api 0.33.0b5

When the server image was stamped with an image tag or a commit, they follow the release in parentheses, for example syn-api 0.33.0 (v0.33.0, abc1234).

Line 2 is different when the server could not say which build it is:

For example, with nothing listening at the URL:

Syntropic137 v0.33.0-beta.1
syn-api not reached at http://127.0.0.1:1: fetch failed

syn version exits 0 in every case: it reports what it found. Use syn health to check that the server is reachable and healthy.

Release skew warning

The CLI and the server match when they share a release line, the major and minor version. Patch and pre-release differences are ignored, so CLI 0.33.0-beta.1 and server 0.33.0b5 match.

When the release lines differ, syn version prints a warning on stderr after line 2:

Syntropic137 v0.32.0
syn-api 0.33.0b5
Warning: syn CLI 0.32.0 is talking to syn-api 0.33.0b5. Releases differ (0.32 vs 0.33); commands may fail in ways that look unrelated. Install a matching CLI.

Every command that talks to the API makes the same check first, so the warning appears before anything the command prints, including its own error:

$ syn execution show exec-2d90c10fbdb3
Warning: syn CLI 0.32.0 is talking to syn-api 0.33.0b5. Releases differ (0.32 vs 0.33); commands may fail in ways that look unrelated. Install a matching CLI.
Execution: exec-2d90c10fbdb3
  Workflow:     Test: PR Review with Comment

The warning only appears when both versions were read and their release lines differ. A server with no GET /version, a server that cannot be reached, or a development build of the CLI never produces it.

When the server predates a command

Two builds on the same release line can still differ by a feature. When a command calls an API route the server does not have, the error names the server build and says the server predates the feature, instead of a bare Not Found:

$ syn execution sessions exec-b6f4c2b271d0
Error: Failed to read session inventory: syn-api 0.33.0b5 at https://syn.example.com has no GET /executions/{execution_id}/session-inventory; this server predates the feature. Upgrade the server to use this command.

If the server cannot report its version either, the error says that instead of naming a release. A 404 for a missing item, such as an unknown execution ID, is unaffected and still reports the server's own message.