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fix: add CODEX_HOME env var to MCP gateway step for Codex engine workflows #27457

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Merged
lpcox merged 2 commits into from
Apr 20, 2026
Merged

fix: add CODEX_HOME env var to MCP gateway step for Codex engine workflows #27457

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a95544a
fix: add CODEX_HOME env var to MCP gateway step for Codex engine work…
lpcox Apr 20, 2026
f90c3ac
chore: start addressing PR review feedback
Copilot Apr 20, 2026
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8 changes: 8 additions & 0 deletions pkg/workflow/mcp_environment.go
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@ import (

"slices"

"github.com/github/gh-aw/pkg/constants"
"github.com/github/gh-aw/pkg/logger"
)

Expand Down Expand Up @@ -189,6 +190,13 @@ func collectMCPEnvironmentVariables(tools map[string]any, mcpTools []string, wor
}
}

// Codex engine needs CODEX_HOME available in the gateway setup step so that
// the converted MCP config can be copied into the writable Codex home directory.
// This matches the value set on the agent step in codex_engine.go.
if workflowData != nil && workflowData.AI == string(constants.CodexEngine) {
envVars["CODEX_HOME"] = "/tmp/gh-aw/mcp-config"
}
Comment on lines +193 to +198
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Copilot AI Apr 20, 2026

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The CODEX_HOME env var is currently gated on workflowData.AI == "codex" (the logical engine ID). This will miss custom engine definitions that are backed by the Codex runtime via engine.definition.runtime-id (supported by the EngineCatalog), and those workflows would still hit the same empty ${CODEX_HOME} failure when the Codex runtime emits CODEX_HOME references in the gateway step. Consider keying this off the resolved runtime adapter instead (e.g., pass the CodingAgentEngine into collectMCPEnvironmentVariables and check engine.GetID() == string(constants.CodexEngine)).

Copilot uses AI. Check for mistakes.

return envVars
}

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37 changes: 37 additions & 0 deletions pkg/workflow/mcp_environment_test.go
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Expand Up @@ -175,3 +175,40 @@ func TestOIDCEnvVarsNotInDockerCommandWithoutOIDCAuth(t *testing.T) {
assert.NotContains(t, output, "-e ACTIONS_ID_TOKEN_REQUEST_TOKEN",
"Docker command should NOT include OIDC env vars without github-oidc auth")
}

// TestCollectMCPEnvironmentVariables_CodexEngineIncludesCODEXHOME verifies that
// CODEX_HOME is included in the MCP gateway step environment for Codex engine workflows
func TestCollectMCPEnvironmentVariables_CodexEngineIncludesCODEXHOME(t *testing.T) {
tools := map[string]any{
"github": map[string]any{
"toolsets": []string{"repos"},
},
}
mcpTools := []string{"github"}
workflowData := &WorkflowData{AI: "codex"}

Comment on lines +187 to +189
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Copilot AI Apr 20, 2026

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This test hardcodes the engine name as the string "codex". To avoid drift with the supported engine IDs, consider using string(constants.CodexEngine) (and similarly for the non-codex cases) so renames/aliases are caught at compile time.

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envVars := collectMCPEnvironmentVariables(tools, mcpTools, workflowData, false)

assert.Equal(t, "/tmp/gh-aw/mcp-config", envVars["CODEX_HOME"],
"CODEX_HOME should be set to /tmp/gh-aw/mcp-config for Codex engine")
}

// TestCollectMCPEnvironmentVariables_NonCodexEngineExcludesCODEXHOME verifies that
// CODEX_HOME is NOT included for non-Codex engine workflows
func TestCollectMCPEnvironmentVariables_NonCodexEngineExcludesCODEXHOME(t *testing.T) {
tools := map[string]any{
"github": map[string]any{
"toolsets": []string{"repos"},
},
}
mcpTools := []string{"github"}

for _, engine := range []string{"copilot", "claude", ""} {
t.Run("engine="+engine, func(t *testing.T) {
workflowData := &WorkflowData{AI: engine}
envVars := collectMCPEnvironmentVariables(tools, mcpTools, workflowData, false)
assert.NotContains(t, envVars, "CODEX_HOME",
"CODEX_HOME should not be set for %s engine", engine)
})
}
}
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