fix(bake): strip model-conditional betas from baked base set

[askalf]

What

Follow-up to #485, required before re-baking on the runner (issue #484).

#485 made the drift detection (computeDrift) ignore the betaForModel()-managed betas. But the bake path (capture-and-bake.mjs) still wrote the raw captured anthropic_beta verbatim — scrubTemplate preserves it by design. So the first auto-rebake after #485 (PR #486, closed) correctly dropped afk-mode-2026-01-31 but re-added context-1m-2025-08-07 to the base set, undoing #475's model-conditional design.

Fix

capture-and-bake.mjs now runs the scrubbed anthropic_beta through a new shared helper stripModelConditionalBetas (exported from drift-report.mjs, backed by the same MODEL_CONDITIONAL_BETAS set the detector uses) before writing the template. The baked base set therefore never carries the per-request betas; betaForModel() re-adds them at request time exactly as #475 intended. The bake logs the strip when it changes anything.

Detection and bake now share one source of truth, so a re-bake can't drift back from what the check expects.

Tests

test/bake-drift-report.mjs +2 cases (now 88/88): stripModelConditionalBetas removes context-1m/fallback-credit while preserving base order and no-opping when absent; and a bake-vs-check consistency case proving computeDrift(baked-base, capture) is empty on the managed betas after the strip.

After this merges

Re-dispatching the drift watcher produces a rebake PR whose only anthropic_beta change is dropping afk-mode (real drift) — no context-1m re-add — plus the system_prompt refresh. That's the clean, canonical runner bake.

[github-actions]

Compat test: ✅ PASSED

Ran node test/compat.mjs against dario proxy --passthrough on the self-hosted runner for commit 763dd8a2a300b349be7ef6db2830b1d76149cbff.

Output

============================================================
  dario Compatibility Validation (--passthrough via dario)
  2026-06-10T11:46:50.163Z
============================================================

--- Anthropic Messages API (Hermes) ---
✅ #1 Anthropic non-stream: "COMPAT OK" | thinking_injected=false | service_tier=-
✅ #2 Anthropic stream: 8 events | order=correct | "**STREAM COMPAT**"
✅ #3 SSE framing: event:/data: pairs correctly paired

--- Passthrough Verification ---
✅ #4 No thinking injection: No thinking block in response (passthrough clean)
✅ #5 Client betas preserved: Client-requested thinking honored (status=200)

--- Tool Use (OpenClaw) ---
✅ #6 Tool use: tool=get_weather | input={"location":"Tokyo"}
✅ #7 Tool use stream: 12 events | tool_use=true | input_json_delta=true

--- OpenAI Compat ---
✅ #8 OpenAI non-stream: "OPENAI COMPAT"
✅ #9 OpenAI stream: 3 chunks | [DONE]=true | "**STREAM OPENAI**"

--- Header Visibility ---
✅ #10 Header visibility: request-id=true | ratelimit=true (12 headers)

============================================================
  RESULTS: 10 passed, 0 failed, 0 warnings
============================================================

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