user_story:
title: "Multiplexed Customer-Specific Modernization Framework in Emacs"
as_a: "platform engineer"
i_want: "a modernization framework implemented entirely in Emacs with a stable core major mode, customer-specific minor modes, and multiplexed buffer-level execution contexts"
so_that: "I can tune behavior per customer without duplicating code while keeping the system extensible, scalable, and regression-safe"
functional_requirements:
core_major_mode:
- "Provide shared modernization logic"
- "Expose hooks for pre-scan, post-scan, and transformation phases"
- "Maintain stable public APIs"
customer_specific_minor_modes:
- "Define buffer-local variables"
- "Encode environment constraints"
- "Provide advice wrappers for restricted environments"
- "Must not modify the core major mode"
multiplexing:
- "Support multiple customer contexts running simultaneously in separate buffers"
- "Each buffer maintains its own active minor modes and local variables"
- "Switching buffers switches customer context automatically"
extensibility:
- "New customers can be added without modifying existing code"
- "All extension points must use hooks or advice"
definition_of_done:
core_implementation:
- "modernization-mode implemented as a derived major mode"
- "Customer-specific minor modes implemented with buffer-local configuration"
- "Multiplexing validated with at least two concurrent customer buffers"
documentation:
- "Inline docstrings for all public functions and variables"
- "README describing how to create a new customer minor mode"
- "Example configuration demonstrating multiplexed buffers"
regression_testing:
framework: "ERT (Emacs Lisp Regression Testing)"
requirements:
- "Automated tests cover major mode initialization"
- "Tests validate minor mode activation/deactivation"
- "Tests confirm buffer-local variable isolation"
- "Tests validate multiplexing behavior across buffers"
- "Tests confirm hook execution ordering"
- "Tests validate advice wrapping behavior"
batch_command: |
emacs -Q --batch -l ert -l tests.el -f ert-run-tests-batch-and-exit
quality_gates:
- "No byte-compiler warnings"
- "All public APIs marked stable"
- "All tests green"
- "Adding a new customer minor mode requires zero changes to the core major mode"
+---------------------+
| Publisher |
| (Subject) |
+---------------------+
|
| notify(event)
v
+---------------------+
| Interceptor |
| (InterceptingFilter)|
+---------------------+
|
| forward(event)
v
+---------------------+
| Subscriber |
| (Observer) |
+---------------------+
Legend:
- Observer Pattern: Publisher → Subscriber
- Interceptor Pattern: Interceptor inserted between Publisher and Subscriber
- Interceptor can:
• Inspect or modify the event
• Block or short-circuit the dispatch
• Log, transform, or enrich the message
+--------------------+
| Observer |
| (reacts to event) |
+--------------------+
/\
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
+--------------------+ +----------------------+
| Interceptor |<--->| Shared Concerns |
| (filters event) | | - Message awareness |
+--------------------+ | - Decoupled wiring |
| - Cross-cutting |
| behavior |
+----------------------+