Implement scan differential notifications with historical change tracking

[techmore]

Summary

Add differential scan analysis so users can compare current results to historical scans and quickly see what changed, when it first appeared, and how long it has persisted.

Why It Matters

The application already stores scan metadata and historical scan artifacts. The missing piece is turning that history into actionable change tracking for operators.

Desired Outcome

• compare a new scan against the most relevant previous scan
• detect new or removed hosts
• detect port, service, and vulnerability changes
• attach basic historical context such as first seen, last seen, and duration where practical
• surface important changes in the UI and reports

Scope

1. Baseline Selection

• define the canonical previous-scan selection logic
• decide how customer/target matching works for comparison

2. Diff Engine

• compare hosts, ports, services, and vulnerability findings
• classify additions, removals, and modifications
• avoid noisy output for insignificant churn where possible

3. Presentation

• show high-signal change summaries in the UI
• include a differential summary in generated reports
• leave room for future alerting without requiring it in the first version

Implementation Notes

Likely touch points in the current architecture:

• scan metadata and persistence helpers
• reporting pipeline
• history/scans API surfaces
• frontend views for scan history and report summaries

This should build on the existing saved-scan/reporting model rather than introducing a parallel history system.

[techmore]

Audit note: this is the clearest root issue behind the current monitoring-related feature requests. It overlaps with #11 (monitoring hub UI) and informs part of #28 (scheduled scan awareness). Recommend using #32 as the core backend/data initiative for change detection and historical diffing, then layering the Dragnet card redesign and countdown/banner work on top rather than implementing each separately.

[techmore]

Implemented the first #32 backend increment on codex/layout-audit.

What landed:

• added baseline selection and asset diff helpers in nmapui/reporting.py
• /api/scans now attaches a diff_summary for scans that have a previous saved scan with the same customer and target
• the first version reports:
  • baseline path/timestamp
  • added hosts
  • removed hosts
  • changed hosts
  • new/removed ports
  • new/removed vulnerabilities
• this builds on the existing saved-scan metadata and XML parsing model; no parallel history system was introduced

Verification:

• ./.venv/bin/python -m pytest -q /Users/techmore/projects/NmapUI/tests/test_reporting_modules.py /Users/techmore/projects/NmapUI/tests/test_auth_routes.py -> 20 passed
• ./.venv/bin/python -m pytest -q -> 141 passed

Commit: 9ecdb5c Add scan diff summaries
Branch: codex/layout-audit

[techmore]

Added the next UI increment on \ in commit 66c6052. The history renderers now surface \ directly in the scan cards, including baseline time plus counts for added/removed/changed hosts, port changes, and vulnerability changes. This also removes the leftover nested page-shell wrapper from the history card details and pins the contract in . Verification: ........................................................................ [ 51%]
..................................................................... [100%]
141 passed in 0.30s -> 141 passed.

[techmore]

Added the next UI increment on codex/layout-audit in commit 66c6052. The history renderers now surface diff_summary directly in the scan cards, including baseline time plus counts for added/removed/changed hosts, port changes, and vulnerability changes. This also removes the leftover nested page-shell wrapper from the history card details and pins the contract in tests/test_runtime_contract.py. Verification: ./.venv/bin/python -m pytest -q -> 141 passed.

[techmore]

Added the report-output increment on codex/layout-audit in commit 33b1b4b. The reporting layer now computes a baseline diff against the previous matching saved scan, injects a scan-diff-summary section into both generated HTML variants, and carries that through both the live report workflow and the saved-PDF workflow. Added direct reporting tests for baseline selection and HTML injection plus a workflow regression to keep the generated report path diff-aware. Verification: ./.venv/bin/python -m pytest -q -> 145 passed.

[techmore]

Added the report-completion UX increment on codex/layout-audit in commit e3e0fa9. Both report-generation paths now include diff_summary in the report_complete payload, and static/js/discovery_ui.js formats the success status message to call out detected changes instead of showing only the scan directory. Added coverage to keep the payload and frontend formatter wired together. Verification: ./.venv/bin/python -m pytest -q -> 145 passed.

[techmore]

Added the history-filter increment on codex/layout-audit in commit c423e6e. The history modal now has a Changed scans only toggle, and static/js/history_modal.js applies it against scan.diff_summary.has_changes after the existing customer/date filters. Added a runtime-contract assertion so the filter stays on the extracted history module path. Verification: ./.venv/bin/python -m pytest -q -> 145 passed.

[techmore]

Implemented on codex/layout-audit across commits 9ecdb5c, 66c6052, 33b1b4b, e3e0fa9, and c423e6e. The repository now has differential scan summaries in the scans API, history cards, generated report HTML/PDF, completion status messaging, and history filtering for changed scans.