LegacyLens — Agentic Software Modernization

Agentic legacy-code migration with program analysis, dependency intelligence, Qdrant-backed retrieval, migration planning, context-grounded conversion, and post-migration release gates.

LegacyLens analyzes a legacy repository, builds a structured representation of its codebase, creates a migration plan, performs context-grounded code transformation, and evaluates the resulting target project with deterministic engineering checks.

What changed in the portfolio-ready release

Developer workbench UI

LegacyLens is intentionally presented as a developer migration workbench, not a generic dashboard:

• Migration-oriented workspace and live workflow stages
• Before/after change exploration
• Release-readiness presentation
• Ask-the-codebase workspace
• Persistent migration/task context
• Hosted-safe Streamlit sidebar collapse/reopen behavior
• System-adaptive light/dark theme with live switching
• Failure states expose a downloadable failure report instead of leaving the user at a dead end

Live migration telemetry

The task lifecycle is explicitly bound to its backend task ID so workflow progress events can update the task being polled by the UI.

Migration request
      ↓
Task created + bound
      ↓
Scanner / planning / conversion progress
      ↓
Task status endpoint
      ↓
Live migration workspace

Reliability / release behavior

The migration platform now has stronger failure handling around the hosted LLM gateway and artifact generation:

• Gateway rate-limit failures are surfaced as real migration failures rather than fabricated code.
• Invalid/empty model output is rejected instead of being treated as generated source.
• Directory-like output paths are normalized defensively.
• Release readiness is derived from the post-migration quality gate.
• A blocked/failed migration can still produce a clearly labeled failure report when no valid migration artifact exists.
• Hosted execution can use lightweight workflow settings to reduce unnecessary agent-event retention.

Architecture

Legacy Repository
       ↓
Program Analysis
  AST / CTags / dependencies / stack detection
       ↓
Knowledge Base
  Qdrant + metadata-aware retrieval
       ↓
Migration Planning
  target architecture + symbol/file mapping
       ↓
Agentic Conversion
  context-grounded transformations
       ↓
Post-Migration QA
  structural + executable validation
       ↓
Release Gate
  ready / blocked / review
       ↓
Migration artifact or failure report

Core capabilities

• Multi-language source scanning
• AST / tree-sitter analysis
• Universal CTags symbol extraction
• File and symbol dependency analysis
• Technology/framework detection
• Qdrant-backed analysis retrieval
• Planning before conversion
• Agentic code transformation
• Deterministic post-migration QA
• Release gates and repair loops
• Evidence-backed migration reports
• Ask-the-codebase retrieval over migration artifacts

BYOK / shared LLM Gateway

LegacyLens uses the portfolio's shared LLM Gateway for request-scoped inference sessions.

Portfolio BYOK
      ↓
Short-lived gateway session
      ↓
LegacyLens
      ↓
Portfolio LLM Gateway
      ↓
Selected provider / model

Provider credentials remain outside the project frontend/source repository.

Local development

cp .env.example .env
docker compose up --build

Testing

python -m pytest -q
python portfolio_quality/quality_gate.py .

Limitations

LegacyLens is a portfolio and engineering demonstration, not a turnkey enterprise migration service. Semantic equivalence remains difficult to prove automatically, so the system exposes structural signals, executable checks, release gates, and review-oriented evidence rather than pretending an LLM confidence score proves correctness.

Portfolio positioning

Developer modernization workbench — program analysis, retrieval-grounded planning, agentic conversion, executable validation, and release-aware migration workflows.