fix(providers): preserve custom model descriptors and restore Copilot startup

[aaditagrawal]

The upstream model editor can write named/custom-option descriptors, but fork-only provider schemas accepted only strings. Saving those settings could make an entire instance unavailable. Accepts the shared backward-compatible model setting across all fork schemas, Copilot driver settings, and ACP config types; preserves labels/options and legacy strings.

Also repairs two live Copilot startup failures: a narrow patch corrects extensionless native ESM imports in the pinned SDK, and a shared resolver stops passing the default command basename as an SDK filesystem path. Applies to health, sessions, model discovery, and usage. No dependency version upgrade.

Validation: regression matrix covers all 16 built-in driver schemas and legacy settings/patches; 147 focused compatibility tests and 11 final SDK/path tests passed. Native Node24 SDK starts/stops without a model turn; two previously skipped adapter tests now run. Full workspace check/typecheck passed. Integrated UI saves a named Copilot model, retains it through restart, and reaches correct signed-out provider health without schema/import failures. Full server run passed 4,073 tests before the final narrow CLI-path change; its affected suites passed afterward.

[aaditagrawal]

• sync: finish upstream alignment through bc8584bf8e #273
• fix(providers): preserve custom model descriptors and restore Copilot startup #272 👈 (View in Graphite)
• refactor(web): remove unused legacy client modules #271
• perf(cursor): retain compact turn summaries instead of SDK streams #270
• fix(providers): reject unsupported rewind before restoring files #269
• sync: complete upstream alignment through 7a089b2b24 #268
• sync: adopt upstream streaming and persistence performance work #267
• sync: integrate remaining upstream commits through 09d13de43 #266
• sync: integrate upstream wave 4 (settings reorg, usage limits, compaction) #265
• sync: integrate upstream wave 3 (Antigravity + cookie import) #264
• sync: integrate upstream wave 2 through 652515a34 #263
• sync: integrate upstream wave 1 through 355fbd96d #262
• main

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	7.0 KiB	—	7.3 KiB	✅
Codex	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	57.0 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	8	—	21	✅
Claude	Total thread wire	—	13.5 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	7.0 KiB	—	7.3 KiB	✅
Claude	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	57.8 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	8	—	21	✅

Baseline: unavailable · PR result: 5086d4b · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 113.9 KiB
• Claude decoded thread snapshot: 114.6 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[aaditagrawal]

Merge activity

• Sep 5, 7:41 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Sep 5, 7:43 AM UTC: Graphite couldn't merge this pull request because a downstack PR sync: integrate upstream wave 2 through 652515a34 #263 failed to merge.