Introduce active_conditions wire format

[robacourt]

Summary

Introduces the active_conditions wire format as a backward-compatible protocol addition, extracted from #3791. This allows clients to be updated to the new protocol before the server adds complex OR/NOT subquery support.

Part of the work toward supporting arbitrary boolean expressions in WHERE clauses (#3791).

Changes

Elixir Client (taken from #3791)

• Tag format: Tags become {position, hash} tuples with slash-delimited wire format (e.g. "hash_a/hash_b", "hash_a/", "/hash_b")
• active_conditions tracking: Headers now include active_conditions: [boolean()] indicating which disjuncts are satisfied
• DNF visibility: Row visibility evaluated as OR of ANDs over positions — a row is visible if at least one disjunct is fully satisfied
• disjunct_positions: Derived once from the first tagged message and reused for all subsequent messages in the shape

Server (minimal changes for current simple case)

• Add active_conditions field to NewRecord, UpdatedRecord, DeletedRecord structs
• Include active_conditions in JSON response headers when present (via put_if_true)
• For shapes with subqueries, set active_conditions: [true, ...] (always all-true in the simple single-subquery case)
• Include active_conditions in snapshot SQL queries alongside tags
• Read Electric-Protocol-Version header from HTTP requests into params schema

Test updates

• 26 new/updated tag_tracker unit tests covering position-based tags, DNF visibility, orphan cleanup, mixed rows
• Removed one integration test that used an unrealistic tag format incompatible with the new wire protocol

Compatibility

• v1 clients (old): Will receive active_conditions in headers but ignore it (unknown field). No regression.
• v2 clients (new Elixir client): Will use active_conditions for DNF visibility. For the simple case (single subquery), behavior is identical to v1 but through the new code path.

Test Plan

• Elixir client: 10 doctests, 206 tests, 0 failures
• Sync service: 382 doctests, 8 properties, 1433 tests, 0 failures
• Router integration: 76 tests, 0 failures

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Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 95.12195% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.89%. Comparing base (b9c7ba7) to head (9a71d29).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...s/elixir-client/lib/electric/client/tag_tracker.ex	94.59%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3966       +/-   ##
===========================================
+ Coverage   75.75%   85.89%   +10.13%     
===========================================
  Files          11       51       +40     
  Lines         693     3403     +2710     
  Branches      173      610      +437     
===========================================
+ Hits          525     2923     +2398     
- Misses        167      478      +311     
- Partials        1        2        +1     

Flag	Coverage Δ
elixir	78.83% <95.12%> (?)
elixir-client	78.83% <95.12%> (?)
packages/experimental	87.73% <ø> (ø)
packages/react-hooks	86.48% <ø> (ø)
packages/start	82.83% <ø> (ø)
packages/typescript-client	93.93% <ø> (?)
packages/y-electric	56.05% <ø> (ø)
typescript	88.74% <ø> (+12.98%)	⬆️
unit-tests	85.89% <95.12%> (+10.13%)	⬆️

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[blacksmith-sh]

Found 1 test failure on Blacksmith runners:

Failure

Test	View Logs
at line 12:44:24 in shell pg/at line 12:44:24 in shell pg	View Logs