GitLab dispatch missing RETRO_COMMENT env var

[ggallen]

Problem

The GitLab dispatch pipeline does not pass RETRO_COMMENT as an environment variable. The retro harness (retro.yaml) references it in env.sandbox via "${RETRO_COMMENT}", and the fullsend CLI's env validation treats any ${VAR} reference as required — causing the run to fail immediately.

Error: validating env: env.sandbox[RETRO_COMMENT]: host variable RETRO_COMMENT is not set (referenced in "${RETRO_COMMENT}")

RETRO_COMMENT is optional — it's only set when a human types /fs-retro <comment>. Most retro runs are dispatched programmatically without it.

Evidence

Failed pipeline: https://gitlab.cee.redhat.com/gallen/integration-service/-/pipelines/17173747 (job 59195029)

Related

• GitLab retro dispatch does not pass required env vars to pipeline #6418 — same class of issue (GitLab dispatch env var gap for ORIGINATING_URL)
• feat: make retro agent multi-forge (GitHub + GitLab) agents#816 — retro multi-forge PR that exercises the GitLab dispatch path

Fix options

1. Update the GitLab dispatch to pass RETRO_COMMENT="" as a default
2. Support optional env var references in the harness engine (e.g., treat vars with no value as empty string instead of erroring)

[fullsend-ai-triage]

🤖 Finished Triage · ✅ Success · Started 6:18 PM UTC · Completed 6:24 PM UTC

Commit: b294e1e · View workflow run →

[fullsend-ai-triage]

Triage

Severity: High — GitLab retro agent is non-functional for programmatic dispatches.

PR #6419 (merged for #6418) added RETRO_COMMENT extraction from EVENT_PAYLOAD_B64 in the scaffold template, but enrolled repos need re-enrollment to pick up that change. A more robust fix at the dispatch or engine level would decouple the fix from scaffold deployment timing.

Recommended approach:

1. Quick fix (dispatch.go): Add RETRO_COMMENT: "" to the variables map for retro-stage dispatches. Add it to signedDispatchKeys for HMAC integrity. This works immediately without scaffold re-deployment.
2. Structural fix (harness.go): Support optional ${VAR} references in ValidateRunnerEnvWith — treat unset optional vars as empty strings rather than erroring. This prevents the same class of issue for future optional variables.

Both approaches complement the existing scaffold extraction (lines 294-298 of fullsend-agent.yml).

Proposed test:

func TestValidateRunnerEnv_OptionalRetroComment(t *testing.T) {
    h := &Harness{
        Env: &EnvConfig{
            Sandbox: map[string]string{
                "RETRO_COMMENT": "${RETRO_COMMENT}",
            },
        },
    }
    // RETRO_COMMENT not set in environment
    err := h.ValidateRunnerEnvWith(func(key string) (string, bool) {
        if key == "RETRO_COMMENT" {
            return "", false // not set
        }
        return "", false
    })
    // After fix: should pass (not error)
    assert.NoError(t, err)
}

Related: #6418 (same class, closed), fullsend-ai/agents#816 (retro multi-forge, open).

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Labels: This is a bug in the retro agent's GitLab dispatch path. Matches type/bug and agent/retro labels based on repo conventions. The sibling issue #6418 used the same labels.

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Next steps:

• /fs-code — agent creates a PR to implement this issue
• /fs-code <your instruction> — agent implements with your specific guidance

[fullsend-ai-coder]

🤖 Finished Code · ✅ Success · Started 6:26 PM UTC · Completed 6:37 PM UTC

Commit: ff93b07 · View workflow run →

[ggallen]

Resolved — the extraction block in fullsend-agent.yml (lines 296-299) already handles RETRO_COMMENT for the retro stage by extracting it from EVENT_PAYLOAD_B64. The failure was caused by the test repo running a stale CI config. After re-enrollment, retro runs succeed without dispatch-level changes.