test: replace source-regex extraction contracts with behavioral assertions

[Astro-Han]

The #1084 refactor wave itself left behind a cluster of *-extraction-contract.test.ts files (born 2026-07-16 – 07-20) that pin source-text layout, not behavior, via readFile + dozens of assert.match/assert.doesNotMatch regexes:

• packages/runtime/src/__tests__/tool-runtime-extraction-contract.test.ts (95 regex assertions)
• packages/runtime/src/__tests__/ai-sdk-compaction-extraction-contract.test.ts (66)
• packages/core/src/__tests__/settings-extraction-contract.test.ts (28)
• packages/runtime/src/__tests__/active-full-compact-extraction-contract.test.ts
• packages/headless/src/__tests__/oracle-registry-workflow-contract.test.ts

A rename or reformat breaks them; a behavioral regression passes them. session-manager.test.ts:8491 similarly pins runtime-kernel.ts internals by slicing source text (indexOf('private async *runAgentTurn') → includes('new AiSdkFlow')).

Scope

Replace each with (a) typed assertions on the extracted collaborator's public interface and (b) the lane's behavioral tests; delete the regex layer. Keep genuinely defensive source guards — containment-guard-contract.test.ts exists to prevent re-definition of a retired predicate and is fine as-is.

Policy for new extraction PRs (effective immediately): upcoming sub-issue PRs under #1084 and the third-pass governance issue should not add new source-regex extraction contracts. Pin an extraction with typed interface assertions and behavior tests instead.

Direction discussion (maintainer input wanted)

apps/desktop/src/main/__tests__ has a larger pre-existing family (~45 behavioral/wiring tests fed by renderer-shell-source-helpers.ts) asserting renderer wiring by regex over source text. Migrating those is a bigger project with real trade-offs (some assert cross-process wiring that is genuinely awkward to execute). This issue proposes agreeing on a policy — no new source-regex behavior tests; migrate opportunistically when a pinned file is refactored — rather than a big-bang rewrite.

References

#1084 (second-pass governance; the wave that introduced the cluster).

[Astro-Han]

I plan to take the two #1381-adjacent runtime files listed here: tool-runtime-extraction-contract.test.ts and ai-sdk-compaction-extraction-contract.test.ts. I’ll replace their source-regex coverage with typed and behavioral contracts, and leave the other #1403 files untouched.

[Astro-Han]

The five source-regex test files are gone: #1448 replaced two of them with typed behavioral coverage, #1727 removed the other three, and #1675 dropped the slice assertions in session-manager.test.ts. What remains is policy discussion, not actionable work.