Builtin compaction omits x-opencode-session for opencode providers → 400 MissingSessionID

[grim-susemi]

Symptom

Any session running an opencode-backed model (for example, opencode-go/muse-spark) fails blocking compaction with:

Compaction rejected: compaction generator failed: OpenAI API error (400) {"type":"MissingSessionID","message":"Error from provider (Console Go): Request is missing x-opencode-session ..."}

Root cause

generateSummaryMessage in src/core/extensions/builtin/compaction/speculative-summary.ts streams via modelRuntime/compat using only auth/transformHeaders headers and never merges provider attribution headers, unlike the normal turn path (sdk.ts transformHeaders -> mergeProviderAttributionHeaders). Therefore no x-opencode-session reaches Console Go.

createOpenAiRemoteCompactionHeaders in openai-remote-model.ts also only forwards sessionId for openai-codex-responses.

Evidence

A diagnostic run showed provider opencode-go, API openai-responses, base URL host opencode.ai, and a session ID present, but final headers without x-opencode-session. After merging attribution headers and directly setting the header, compaction succeeded: the header was present and the session compacted cleanly.

Suggested fix direction

Merge mergeProviderAttributionHeaders into the compaction summary request headers (guard for settingsManager being unavailable in that context), or set x-opencode-session directly for opencode providers. Happy to submit a PR if maintainers agree on the direction.

Environment

• omo-ai 5.0.0-0.beta.50 / senpi 2026.9.9
• Windows x64
• opencode-go/muse-spark-1.3-contributor session

[Altairpaca]

I re-checked this against current main (b057a4f6791f2f4f5ee844da19c31af9435f07ac): generateSummaryMessage() still dispatches through ModelRuntime.stream() after extension request transforms, while the x-opencode-session attribution is still added only by the normal sdk.ts path. There is no linked PR yet.

If the reporter is not already implementing this, I can take the patch. I’ll keep it narrow: reuse the existing provider-session attribution logic rather than hard-code an opencode-go special case in compaction, pass the active session id only at the compaction request boundary, and add a deterministic regression that proves summarization carries x-opencode-session without changing non-OpenCode providers. I’ll also preserve the existing header precedence / extension transforms and update the nearest changes.md per the repo contract.

[Altairpaca]

Implementation is in #1558 and has been tightened against current main (e66c1553a60917260f480ebab09c817fda73fb14). The patch stays deliberately narrow: builtin summarization seeds the existing OpenCode session-routing defaults at its own ModelRuntime.stream() boundary, then resolved/configured headers and the existing provider-header transform retain override authority. It does not move session attribution into ModelRuntime or special-case a particular model.

The regression is now under test/suite/regressions/ and covers opencode-go, opencode.ai host detection, configured/auth overrides, extension overrides, and unrelated-provider neutrality. A real OmO Native reproduction of the same compact-only failure is also tracked as code-yeongyu/oh-my-openagent#8018; OpenCode has separately tracked the provider-side MissingSessionID enforcement in anomalyco/opencode#47763.

PR remains draft only for repository-contract tracker coverage and executable CI evidence; the external-contributor workflow is currently gated before jobs run.