Capture chain exchange messages in F3 observer

[masih]

Add the ability to capture chain exchange messages via F3 observer and make them queryable via SQL statement.

The captured chain exchange messages offers a mapping of EC chain key to the concrete EC chain value itself, since partial GMessages only contain the EC chain key and not the chain itself.

Fixes #970

[Copilot]

Pull Request Overview

This PR adds support for capturing and persisting chain exchange messages in the F3 observer pipeline so they can be queried via SQL.

• Introduces a new chain_exchanges table in the SQL schema.
• Adds options and CLI flag to configure chain exchange observation.
• Implements in-process handling, batching, and storage of chainexchange.Message values.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
observer/schema.sql	Added chain_exchanges table for persisting chain exchange data
observer/options.go	Added chainExchangeBufferSize and chainExchangeMaxMessageAge options
observer/observer.go	Implemented observeChainExchanges, storage logic, and pubsub validator
observer/model.go	Defined ChainExchange model and constructor
cmd/f3/observer.go	Exposed chainExchangeMaxMessageAge flag to the CLI

Comments suppressed due to low confidence (3)

cmd/f3/observer.go:128

• [nitpick] Consider adding a corresponding CLI flag (e.g. --chainExchangeBufferSize) to allow users to configure the buffer size for chain exchange messages, matching the new WithChainExchangeBufferSize option.

		&cli.DurationFlag{

observer/observer.go:773

• The code uses sync.WaitGroup here but sync is not imported at the top of the file. Add import "sync" to avoid a compile error.

	var wg sync.WaitGroup

observer/schema.sql:98

• The schema defines VoteValue as a STRUCT array, but the insertion uses a JSON cast (?::json). Either change the column to JSON/JSONB or adjust the insert to match the STRUCT type.

  VoteValue STRUCT(

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 205 lines in your changes missing coverage. Please review.

Project coverage is 65.68%. Comparing base (00ff781) to head (fa92fcf).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
observer/observer.go	0.00%	180 Missing ⚠️
observer/options.go	0.00%	16 Missing ⚠️
observer/model.go	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1031      +/-   ##
==========================================
- Coverage   66.91%   65.68%   -1.24%     
==========================================
  Files          80       80              
  Lines        9510     9706     +196     
==========================================
+ Hits         6364     6375      +11     
- Misses       2652     2838     +186     
+ Partials      494      493       -1     

Files with missing lines	Coverage Δ
observer/model.go	0.00% <0.00%> (ø)
observer/options.go	6.00% <0.00%> (-0.45%)	⬇️
observer/observer.go	0.00% <0.00%> (ø)

... and 6 files with indirect coverage changes

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