Module prompt engineering Roadmap

Prompt Engineering Module Roadmap

Current Status

Production-capable prompt engineering runtime exists for template lifecycle operations, context injection, revision/version control, optimization/evaluation loops, feedback ingestion, and prompt metrics support.

In Progress

• hardening adversarial/edge-case template and injection validation behavior (Target: Q3 2026) — COMPLETED 2026-08-08
• [~] improving optimization/evaluation diagnostics consistency across failure classes (Target: Q3 2026)
• [~] stabilizing benchmark-backed release guardrails for prompt engineering hot paths (Target: Q3 2026)

Planned Features

Short-term (3-6 months)

• tighten deterministic behavior for concurrent template/version mutation traffic (Target: Q4 2026)
• expand stress coverage for optimization loops and feedback-heavy scenarios (Target: Q4 2026)
• improve operator-facing diagnostics for prompt incident triage (Target: Q4 2026)
• introduce deterministic RewriteEngine for prompt normalization, policy rewrites, and NL→AQL preprocessing (Target: Q4 2026)

Mid-term (6-12 months)

• re-baseline p95/p99 envelopes for prompt template/version/quality paths (Target: Q1 2027)
• broaden benchmark depth for module-native advanced prompt workflows (Target: Q1 2027)
• harden long-run reliability under sustained prompt update/evaluation pressure (Target: Q1 2027)
• extend RewriteEngine to post-generation canonicalization and structured agent/tool output normalization (Target: Q1 2027)

Implementation Phases

Phase 1: Design / API Contract

• freeze template/versioning/optimization contracts for current major line (Target: Q3 2026) — See PHASE_1_CONTRACT.md
• define explicit error taxonomy for prompt engineering failure classes (Target: Q3 2026) — See ERROR_TAXONOMY_REFERENCE.md and prompt_engineering_errors.h (52 error codes)
• define RewriteEngine interfaces (RewriteDocument, RewriteContext, RewriteResult, RewriteTrace, IRewriteRule) and phase boundaries (Target: Q4 2026) — See rewrite_engine.h

Phase 2: Core Implementation

• complete hardening for manager/version control and validator internals (Target: Q4 2026) — PHASE_1_CONTRACT.md baseline established
• align optimization/evaluation behavior to bounded runtime contracts (Target: Q4 2026) — baseline contracts defined
• implement deterministic ordered rule execution, rule registration, and YAML-backed low-risk rewrite loading (Target: Q4 2026) — RewriteEngine implementation complete
  • rewrite_engine.cpp: Core orchestration with phase ordering, priority-based execution, max-steps prevention
  • rewrite_rule_base.cpp: Concrete rule types (RegexRewriteRule, DictionaryRewriteRule, PolicyRewriteRule, SemanticRewriteRule)
  • rewrite_rule_loader.cpp: YAML schema validation and lexical rule loading
  • rewrite_metrics.cpp: Observability with per-rule and per-phase metrics
• implement RewriteEngine executor with deterministic rule evaluation and phase isolation (Target: Q4 2026) — all 4 phases (input normalization, policy, NL→AQL, post-gen) implemented
• implement YAML configuration schema for input normalization rules (Target: Q4 2026) — regex and dictionary rules with schema validation

Phase 3: Error Handling and Edge Cases

• standardize fail-safe behavior for invalid templates, injection mismatches, and version faults (Target: Q4 2026) — COMPLETED 2026-08-08
  • PromptTemplateValidator extended with injection detection methods
  • SQL, command, path traversal, and template injection patterns detected
  • Adversarial test cases: 54+ malicious payloads covering evasion attempts and edge cases
  • Integration: validate() automatically checks template content for injection patterns
• unify diagnostics across manager/version/optimizer/evaluator incidents using PromptEngineeringErrorContext (Target: Q4 2026)
• enforce rewrite step bounds, phase isolation, malformed-rule rejection, and terminal policy behavior (Target: Q4 2026)
• BATCH 3: Adversarial/Edge-Case Validation (Target: Q3 2026) — COMPLETED 2026-08-15
  • 8 test classes covering: SQL injection, Command injection, Path traversal, XSS, Template recursion, Unicode evasion, Null byte injection, Mixed attacks
  • 54+ malicious payloads for comprehensive injection pattern detection
  • File: tests/prompt_engineering/test_prompt_engineering_adversarial_focused.cpp
  • Target detection rate: 100% on known malicious inputs, <1% false positives on benign prompts

Phase 4: Tests

• [~] expand focused regressions for invalid template and concurrent mutation scenarios (Target: Q4 2026) — Focused test suite PE-FT-001..PE-FT-015 established; BATCH 3 adversarial suite PE-ADV-01..08 complete (2026-08-15)
• [~] extend deterministic stress fixtures for optimization/evaluation workloads (Target: Q4 2026) — Synthetic workload generators implemented; stress test harness ready (2026-08-07)
• [~] add unit/integration coverage for rewrite rule ordering, trace generation, normalization idempotence, and NL→AQL preprocessing flows (Target: Q4 2026) — Rewrite rule test cases drafted; NL→AQL preprocessing validation pending (2026-08-07)

Phase 5: Performance and Hardening

• lock benchmark-backed release gates for prompt engineering hot paths (Target: Q4 2026) — Complete: bench_prompt_engineering.cpp (PromptManager/VersionControl/Optimizer/Evaluator gates) + bench_rewrite_engine.cpp (PEG-01..06 RewriteEngine gates) delivered (2026-08-07)
• [~] validate p95/p99 and throughput behavior against release baselines (Target: Q4 2026) — Benchmark suite ready for execution; p95/p99 validation in progress (2026-08-07)
• [~] benchmark rewrite latency/trace overhead and harden regex/rule execution against adversarial expansion or loop behavior (Target: Q4 2026) — PEG-04..06 (rule loading, trace gen, step limits) implemented; adversarial testing in progress (2026-08-07)

Phase 6: Documentation and Acceptance

• core prompt_engineering docs aligned to source-verifiable behavior (Target: Q3-Q4 2026) — Complete with Phase 1-2 deliverables
• roadmap/future planning separated from historical changelog entries
• focused test infrastructure (PE-FT-001..PE-FT-015) implemented at tests/prompt_engineering/test_prompt_engineering_focused.cpp (Target: Q3 2026)
• document and integrate rewrite engine architecture and operational guidance (docs/architecture/rewrite_engine_architecture.md) (Target: Q4 2026) — Complete 2026-08-07
• benchmark gates documented: GATE-PE-01..06 (PEG-01..06) in benchmarks/prompt_engineering/bench_rewrite_engine.cpp (Target: Q4 2026) — Delivered 2026-08-07
• [~] acceptance checklist sign-off ready for final human review (Target: Q4 2026)

Production Readiness Checklist

• core prompt engineering surfaces documented and source-verified
• module-level security and failure behavior documented (Phase 1: error taxonomy in prompt_engineering_errors.h and ERROR_TAXONOMY_REFERENCE.md)
• benchmark mapping documented in performance expectations (Phase 5: bench_prompt_engineering.cpp + bench_rewrite_engine.cpp with GATE-PE-01..06)
• focused test infrastructure (PE-FT-001..PE-FT-015) implemented for core surfaces
• [~] remaining hardening tasks in progress for template/versioning/quality edge paths (Phase 3 + Phase 4 work, target completion 2026-08-15)
• [~] release benchmark stabilization in progress (Phase 5 work, target completion 2026-08-15)
• [~] rewrite engine deterministic rule execution, bounded behavior, and audit trace support validated in production-like test profiles (Phase 2–5 work, target completion 2026-08-15)
• backward compatibility guarantee documented and reviewed (Phase 1: PHASE_1_CONTRACT.md)
• RewriteEngine benchmarks with 6 release gates (GATE-PE-01..06) documented and registered (2026-08-07)

Known Issues and Limitations

• runtime behavior depends on template quality, injected context shape, optimizer configuration, and downstream model behavior.
• selected adversarial and concurrency-heavy edge scenarios need continued hardening.
• benchmark depth should continue expanding for advanced prompt engineering workflows.
• rewrite-driven normalization and policy behavior are not yet implemented and remain roadmap work.

Breaking Changes

No breaking prompt engineering contract planned. Any contract-breaking change requires migration notes and changelog entry before merge.

Module Evidence and Validation (Q3 2026 Snapshot)

Focused Test Infrastructure (PE-FT-001..PE-FT-015)

Implemented focused test suite at tests/prompt_engineering/test_prompt_engineering_focused.cpp:

Test ID	Area	Coverage	Status
PE-FT-001	PromptManager template lifecycle	create/get/list operations	✅ PASS
PE-FT-002	Context injection	context map substitution	✅ PASS
PE-FT-003	Template validation	valid/invalid template checks	✅ PASS
PE-FT-004	PromptVersionControl	commit/history operations	✅ PASS
PE-FT-005	FeedbackCollector	feedback recording and stats	✅ PASS
PE-FT-006	PromptOptimizer	basic optimization loop	✅ PASS
PE-FT-007	PromptEvaluator	structural evaluation	✅ PASS
PE-FT-008	PromptEngineeringMetrics	metrics recording	✅ PASS
PE-FT-009	Error handling	missing template edge case	✅ PASS
PE-FT-010	Error handling	invalid context injection edge case	✅ PASS
PE-FT-011	Concurrency	basic concurrent template access	✅ PASS
PE-FT-012	Injection validation	empty placeholder edge case	✅ PASS
PE-FT-013	Version control	commit history consistency	✅ PASS
PE-FT-014	Optimizer diagnostics	diagnostic output validation	✅ PASS
PE-FT-015	Evaluator consistency	multiple evaluation consistency	✅ PASS

Benchmark Evidence (Existing)

• benchmarks/prompt_engineering/bench_prompt_engineering.cpp provides performance validation
• Covers 13 benchmark targets for template operations, context injection, version control, feedback, optimization, and evaluation
• Performance targets documented and tracked (e.g., createTemplate < 10 µs, getTemplate < 1 µs)

Build Targets

• Build (Preset: community-release-allow-missing-rocksdb)

  • module_prompt_engineering_test_prompt_engineering_focused_focused - focused test executable
  • bench_prompt_engineering - benchmark executable

• Test Registry

  • Focused tests registered with: themis_register_module_focused_test(MODULE prompt_engineering TIER unit TIMEOUT 120)
  • CTest labels: prompt_engineering for filtering and aggregation

Validation Summary

• ✅ Roadmap priorities (8 Q3/Q4/Q1 2027 items) synced with ROADMAP.md
• ✅ Future enhancements scope aligned with FUTURE_ENHANCEMENTS.md
• ✅ Core API surfaces tested (template, versioning, feedback, optimization, evaluation, metrics)
• ✅ Error handling and edge cases covered (15 focused test cases)
• ✅ Concurrency sanity check included
• ✅ Benchmark infrastructure exists and measurable against documented targets

Phase 2: RewriteEngine Core Implementation Evidence (2026-08-05)

Implementation Deliverables

Core Engine Implementation

• src/prompt_engineering/rewrite_engine.cpp (495 lines)
  • Phase-ordered deterministic execution (phases 1-4 in strict sequence)
  • Thread-safe rule registration and management with shared_mutex
  • Max-steps loop prevention (default 1000, configurable per context)
  • Rule lookup optimization by phase
  • Trace collection with optional max_trace_entries limit
  • JSON stats export with rule counts, latency, transformation metrics

Concrete Rule Type Implementations

• src/prompt_engineering/rewrite_rule_base.cpp (409 lines)
  • RegexRewriteRule: Precompiled regex patterns with backreference support, max_replacements bound
  • DictionaryRewriteRule: Hash-based substitution with case-sensitive/insensitive modes
  • PolicyRewriteRule: Custom match/apply callbacks for semantic policy enforcement (terminal mode)
  • SemanticRewriteRule: Base class for complex C++-only rule implementations

YAML Rule Loader

• src/prompt_engineering/rewrite_rule_loader.cpp (328 lines)
  • Schema validation for YAML rule definitions
  • Lexical-only constraint enforcement (regex and dictionary rules only from YAML)
  • All-or-nothing loading semantics (partial failures don't modify registry)
  • Phase/priority/mapping validation with detailed error messages
  • Regex compilation validation at load time

Observability

• src/prompt_engineering/rewrite_metrics.cpp (230 lines)
  • Per-rule metrics: match/apply/error counts, min/max/avg latency
  • Per-phase metrics: aggregated rules_evaluated/rules_applied/total_latency
  • Global singleton metrics collection with reset capability
  • JSON export with timestamp for integration with monitoring systems

Test Coverage (RW-P2-01..06)

Test ID	Coverage	Location	Status
RW-P2-01	Rule registration and deduplication	test_rewrite_engine_focused.cpp:45-113	✅ PASS
RW-P2-02	Phase ordering enforcement	test_rewrite_engine_focused.cpp:125-160	✅ PASS
RW-P2-03	Priority-based execution within phases	test_rewrite_engine_focused.cpp:172-207	✅ PASS
RW-P2-04	Max-steps loop prevention	test_rewrite_engine_focused.cpp:219-256	✅ PASS
RW-P2-05	Trace correctness and completeness	test_rewrite_engine_focused.cpp:268-330	✅ PASS
RW-P2-06	Thread-safety under concurrent register/rewrite	test_rewrite_engine_focused.cpp:342-427	✅ PASS

Additional Tests

• Multi-phase execution integration test
• Dictionary rule substitution
• Statistics tracking and JSON export
• 28 focused test cases total covering RW-FT-001..028 scenarios

Header Files Created

• include/prompt_engineering/rewrite_rule.h (238 lines)

  • Interface declarations for all 4 rule types
  • Callback function type aliases for PolicyRewriteRule
  • Doxygen documentation for all public methods

• include/prompt_engineering/rewrite_rule_loader.h (62 lines)

  • RewriteRuleLoader class with load/validate/error reporting
  • All-or-nothing semantics documented

Build Configuration

• src/prompt_engineering/CMakeLists.txt created
  • themis_prompt_engineering_rewrite library target
  • Linked against nlohmann_json, spdlog, yaml-cpp
  • C++17 standard requirement
  • Integrated with test infrastructure via glob pattern in tests/prompt_engineering/CMakeLists.txt

Acceptance Criteria - Phase 2 Complete ✅

• ✅ RewriteEngine core implemented and linked
• ✅ All rule types (regex, dictionary, policy, semantic) compilable and functional
• ✅ YAML loading works for lexical rules with schema validation
• ✅ 6 focused RW-P2 tests passing (28 total test cases)
• ✅ No blocking compile/link errors
• ✅ Thread-safety verified under concurrent operations
• ✅ Deterministic phase ordering enforced
• ✅ Observability metrics collected and exported

Next Steps: Phases 3-6 Parallel Streams

• Stream B (Secondary): Phase 3 error paths (RW-P3-01..04) — can proceed immediately
• Stream C (Tertiary): Phase 4 comprehensive tests (RW-FT-001..060 expansion)
• Stream D (Performance): Phase 5 benchmarking (bench_rewrite_engine.cpp)
• Stream E (Documentation): Phase 6 docs (operational guidance, YAML schema reference)

Program Execution Model — Wave Context

This module is a contributing module in the program-level Wave A → B → C → D execution model. It does not own a primary wave deliverable but must remain release_critical-green throughout all waves and must deliver Wave D operability improvements in Q1 2027. See [[../../ROADMAP.md|ROADMAP]] for the full wave model and exit criteria.

Wave D Contribution for prompt_engineering

• Deliver or validate distributed tracing, high-cardinality stress coverage, exporter reliability, and operator remediation hints as applicable to this module (Target: Q1 2027)
• Contribute to or validate long-duration soak test coverage for this module's primary paths (Target: Q1 2027)
• Ensure runbook coverage for operator-critical scenarios in this module (Target: Q1 2027)

Cross-Wave Requirements

• release_critical CI must remain green on develop throughout all waves (Target: ongoing)
• p95/p99 benchmarks must be refreshed on representative hardware before Wave D sign-off (Target: Q1 2027)
• No behavioral regression may be introduced into modules in Wave A/B/C scope from changes in this module.

Program-Level Success Criteria (contribution)

• This module's distributed/acceleration paths fail closed (Target: Q1 2027)
• Benchmark-backed p95/p99 baselines exist on representative hardware (Target: Q1 2027)
• Operator-critical paths have diagnostics, alerts, and runbooks (Target: Q1 2027)