sharing 3/7: Policies (context → policy → policy_result → action)

[keithharvey]

📚 The sharing stack — review bottom-up

• 1/7 · Transfer library (enums, comms, serialization, test infra) (sharing 1/7: Transfer library (enums, comms, serialization, test infra) #8125)
• 2/7 · Modes & economy boundary (presets, waterfill, share ledger) (sharing 2/7: Modes & economy boundary (presets, waterfill, share ledger) #8126)
• 3/7 · Policies (context -> policy -> policy_result -> action) (sharing 3/7: Policies (context → policy → policy_result → action) #8407) ← you are here
• 4/7 · Transfer runtime (controllers, economy boundary, gadget swap) (sharing 4/7: Transfer runtime (controllers, economy boundary, gadget swap) #8062)
• 5/7 · Tech Core / Keystone (sharing 5/7: Tech Core / Keystone #8063)
• 6/7 · Sharing Tab UI (sharing 6/7: Sharing Tab UI #8064)
• 7/7 · Game modes export (export widget, headless startscript, CI workflow) (sharing 7/7: Game modes export (widget, headless startscript, CI workflow) #8095)

Note

Part of native stack #8411 (feature tracking: #8412). Merges bottom-up through the GitHub stacked-PR UI once the type-migration stack (#8398) is in.

Each PR is file-partitioned: every file appears in exactly one PR in its final sharing_tab form, so each PR's diff is byte-identical to that branch. Regenerated deterministically by just bar::sharing-split.

Summary (LLM-generated, claude-opus-4-6)

Adds the policy evaluation layer: ContextFactory builds a PolicyContext (team resources, alliance, cheating state, extensible via PolicyContextEnricher hooks), which feeds into CalcResourcePolicy / GetPolicy to produce a ResourcePolicyResult or UnitPolicyResult. Transfer actions (ResourceTransfer, UnitTransfer) consume those policy results to execute the actual engine calls. A per-team factor cache (CacheTeamFactor / UpdatePolicyCache) stores O(teams) records that GetCachedPolicyResult reconstructs into any sender-receiver pair on read, keeping the widget side in sync without O(pairs) storage. Unit validation (ValidateUnits) enforces sharing modes, blocks nanoframes of stun-category units, and tallies build-delay and stun counts. Tests cover resource and unit policies, the factor cache, and three concrete modes (enabled, disabled, easy_tax).

[github-actions]

Integration Test Results

14 tests  ±0   6 ✅ ±0   3s ⏱️ ±0s
 1 suites ±0   8 💤 ±0 
 1 files   ±0   0 ❌ ±0 

Results for commit 854b356. ± Comparison against base commit a86685b.

♻️ This comment has been updated with latest results.

[keithharvey]

Superseded by the modules stack: sharing now ships as one de-noised PR — #8463 (modules — multiplayer 2/2: sharing v2), tracked in #8412. Closing this chain; the branch stays for reference.