> ## Documentation Index
> Fetch the complete documentation index at: https://sysg.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Dialog

# Dialog

When something fails, sysg answers like a compiler: what happened, the evidence
it captured while it happened, and the exact next commands to run. Every
user-facing failure is a structured diagnostic with a stable error code.

```text theme={null}
error[SG0104]: service `gamecast_api` failed to become healthy

  5 health checks against http://127.0.0.1:8080/api/v1/health failed over 45s
  the process is not running — it exited before it could become healthy

  last output from `gamecast_api`:
  │ Error: error returned from database: password authentication failed for user "postgres"

  help:
    view logs     sysg logs -s gamecast_api -p gamecast-api-dev
    check status  sysg status -p gamecast-api-dev
    docs          https://docs.sysg.dev/errors/SG0104
```

## Anatomy

Every diagnostic has the same shape:

| Part            | What it tells you                                                 |
| --------------- | ----------------------------------------------------------------- |
| `error[SG0104]` | Severity and a stable code you can search or look up              |
| Title           | One sentence stating what happened                                |
| `-->` location  | The config file and key the problem originates from, when known   |
| Notes           | Plain-sentence facts sysg observed (exit codes, timing, liveness) |
| Evidence        | Output sysg captured — usually your service's own last log lines  |
| `help:`         | Runnable commands and a docs link for this exact code             |

## Colors

On a terminal, diagnostics are colored: red for errors, yellow for warnings,
cyan for notes and locations, green for the help section, bold for runnable
commands, and underlined blue for docs links. Piped or redirected output is
plain text with no escape codes, and `NO_COLOR` is respected.

## Error codes

| Code     | Meaning                                                                |
| -------- | ---------------------------------------------------------------------- |
| `SG0001` | Catchall — a failure that has no more specific diagnosis yet           |
| `SG0102` | A service exited immediately at start, before it finished starting     |
| `SG0103` | A service's `pre_start` command failed, so the service was not started |
| `SG0104` | A service never passed its configured health check                     |
| `SG0201` | The `-p` project does not match the config sysg resolved               |

Codes are stable: a script can match on them, and each has a page at
`https://docs.sysg.dev/errors/<code>`.

## Where evidence comes from

sysg already captures every service's stdout and stderr (see
[Logs](/how-it-works/logs)). Diagnostics quote the last lines of that capture
at the moment of failure, so the reason a service died — a bad database
password, a port conflict, a missing binary — arrives inside the error itself
instead of behind a `sysg logs` round-trip.