Evaluate jpx-engine as JMESPath backend

[joshrotenberg]

Summary

Evaluate replacing jmespath + jmespath_extensions with jpx-engine for a unified, more powerful JMESPath implementation.

Current setup

jmespath = "0.4"
jmespath_extensions = "0.7"

Proposed

jpx-engine = "x.y"

Benefits of jpx-engine

Same engine as jpx CLI and MCP server - consistent behavior across tools.

Core evaluation

• evaluate() - Evaluate JMESPath expression against JSON
• batch_evaluate() - Multiple expressions against same input
• validate() - Check expression syntax with better error messages

Function discovery (could power --help or introspection)

• functions() - List all 320+ functions by category
• describe_function() - Get detailed function info
• search_functions() - Fuzzy search by keyword

JSON utilities (potential new commands)

• format() - Pretty-print JSON
• diff() / patch() / merge() - JSON Patch (RFC 6902) and Merge Patch (RFC 7396)
• stats() - Analyze JSON structure
• paths() - Extract all paths in dot notation

Query store (enables #593)

• define_query() - Store named queries
• run_query() - Execute stored queries
• list_queries() - List all stored queries

This would enable features like:

# Pre-baked query files
redisctl cloud cost-report download $ID -q @queries/focus/top-resources.jmespath

# Named queries
redisctl query define top-costs 'sort_by(@, &BilledCost) | reverse(@) | [:10]'
redisctl cloud cost-report download $ID -q @top-costs

# Introspection
redisctl jmespath functions --category Array
redisctl jmespath describe group_by

References

• jpx-engine docs: https://joshrotenberg.com/jmespath-extensions/libraries/jpx-engine.html
• Related: Support @file syntax for JMESPath queries #593 (query file support)

[joshrotenberg]

Now tracked under #726 (JMESPath epic).