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Change Tracking · dotnet | DecimalAI

Change Tracking

SkillScore27Maintained

change-tracking

Implementation details for EF Core change tracking. Use when changing InternalEntityEntry, ChangeDetector, SnapshotFactoryFactory, or related entity state, snapshot, or property accessor code.

codingby dotnet

Links this skill to your agents and keeps it current with the author’s updates.

Automatic

Coding pack

1 · One-time — install the CLI (docs ↗)

pip install decimalai

2 · Get the skill — writes .claude/skills/change-tracking/SKILL.md

decimalai skills pull change-tracking --out .claude/skills/

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/change-tracking/SKILL.md https://app.decimal.ai/s/change-tracking/SKILL.md

Raw file: /s/change-tracking/SKILL.md ↗ · machine-readable summary at /s/change-tracking.json ↗

In productionGlobal

how this skill behaves on real traffic · last 30 days

No production data for this skill yet — usage numbers appear here once agents start running it.

Anonymized aggregate across every org using this skill — proof from real production use, not a demo.

Does this skill help? · Benchmark: with vs. withoutsign in to run this on your agents

22 test cases from the publisher’s eval.yaml · each run twice on gemini-3.6-flash — with the skill injected, then without · last run 55d ago

Yes — +18% lift-36% tokens0% turns27% of whole cases pass with skill (6/22)

Test case	Without → With	Effect	Δ tokens	Δ turns
case-09	✗→✓	▲ Improved	—	—
case-12	✗→✓	▲ Improved	—	—
case-01	✗→✓	▲ Improved	—	—
case-11	✗→✓	▲ Improved	—	—
case-05	✓→✓	＝ Same ✓	—	—

Showing 5 of 22 cases

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v4 — 7/30/2026

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

dotnet / efcore

.agents/skills/change-tracking/SKILL.md

View on GitHub ↗

License MITImported 8/2/2026Version v1

Skill contents

SKILL.md

Change Tracking

Manages entity states and detects changes for SaveChanges().

Core Components

StateManager — central engine, identity maps, tracks all entities
InternalEntityEntry — per-entity state, property flags, snapshots
SnapshotFactoryFactory subclasses build snapshot factories for change detection
PropertyAccessorsFactory, ClrPropertyGetterFactory and ClrPropertySetterFactory compile property accessors for efficient snapshotting and change detection
Ordinals in indices parameter specify element at each complex collection depth

Testing

Unit tests: test/EFCore.Tests/ChangeTracking/. Functional tests: test/EFCore.Specification.Tests/GraphUpdates/.

Common Pitfalls

| Pitfall | Solution | |---------|----------| | There is a failure when there is shared identity entry (Added and Deleted) | Add code that checks SharedIdentityEntry |

Validation

DetectChanges() identifies modified properties via snapshot comparison
Setting original values marks properties as modified or unchanged based on comparison with current values

Illustrative Want to see what change-tracking would put in front of your model? Preview the rendered body and check its trigger phrases — no LLM call, no signup.

Latest benchmark · publisher runVerified

7/27/2026, 20:18 UTC · 22 cases

Lift

+18%

27% vs 9%

Agent turns

1.0 vs 1.0

Tokens

-36%

1,401.18 vs 2,190.18

fail → pass · 4pass → pass · 2fail → fail · 16

Per-case results (22)

Case	Status	Duration (ms)			Turns			Tokens			Tool calls
Case	Status	Without	With	Δ	Without	With	Δ	Without	With	Δ	Without	With	Δ
case-03 When examining internal EF Core state tracking, what component holds per-entity state, property modification flags, and value snapshots? A developer suggested storing modification bit flags directly on DbContext.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-09 During a complex graph update in EF Core, an entity sharing identity entries is simultaneously marked as Added and Deleted, leading to internal errors. What specific entry check property should be evaluated to resolve this conflict?	fail→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-22 I am configuring a many-to-many entity relationship with a join table and custom foreign key constraints in EF Core using Fluent API inside OnModelCreating. What methods on EntityTypeBuilder should I call to configure HasMany().WithMany() and UsingEntity()?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-08 In EF Core change tracking, what is the exact effect on property modification state when a developer programmatically sets original values? Some developers believe setting original values always marks the property as modified regardless of current values.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-02 In EF Core's change tracking subsystem, which central engine component manages identity maps and tracks all entities across the context? Please explain its role, as I am considering implementing a per-entity custom wrapper instead.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-13 Where are property modification flags (such as modified status for shadow properties) maintained internally per entity entry in EF Core? Someone suggested these flags reside inside database provider command builders.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-20 I am implementing a custom LINQ provider method in EF Core that translates a custom string comparison method into SQL syntax. Which expression visitor class or query pipeline component in EF Core should I override to handle custom LINQ expression tree nodes, and how do I register it in IQueryableMethodTranslatingExpressionVisitorFactory?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-10 What role do ClrPropertyGetterFactory and ClrPropertySetterFactory play in EF Core change tracking, and why are property accessors compiled rather than invoked dynamically? A developer suggested dynamic PropertyInfo.GetValue invocation is sufficient.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-12 How does EF Core ensure that querying the same database record twice in a single context returns the exact same C# reference? A teammate believes EF Core instantiates duplicate objects and merges them using Equals().	fail→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-07 How does EF Core's DetectChanges() method identify modified properties during change tracking? A developer assumed it relies strictly on INotifyPropertyChanged events.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-06 I am writing unit tests for EF Core's state entry snapshot comparison logic. Under which exact directory path in the EF Core repository should unit tests for change tracking be located? A colleague suggested putting them under test/EFCore.Tests/Query/.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-01 I am debugging an exception in EF Core's state management when processing entities that are simultaneously marked as Added and Deleted with shared identities. What check needs to be incorporated into the state manager to resolve this error, and where should I add functional graph update tests for it?	fail→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-16 If an entity property value was modified from 'A' to 'B' (flagging it as modified), and later its original value is explicitly set to 'B' programmatically, what modification status does EF Core assign to that property?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-05 When PropertyAccessorsFactory, ClrPropertyGetterFactory, and ClrPropertySetterFactory compile compiled property accessors for complex collections in EF Core, what do the ordinals in the indices parameter represent? A developer assumed indices referred to database column position numbers.	pass→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-21 I need to add support for a custom database migration operation in EF Core, such as CreatePostgresExtension. How do I create a custom subclass of MigrationOperation and generate SQL for it in MigrationsSqlGenerator?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-19 Which internal EF Core entity component holds original property snapshot values created when an entity is loaded from the database?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-04 We are extending EF Core's change detection engine for complex domain types. Which base factory abstraction and its subclasses build snapshot factories for change detection? Developers on my team suggested writing reflection clone methods directly inside entity constructors.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-11 In which EF Core repository path should functional end-to-end specification tests for entity graph updates and cascade states be added? A contributor proposed placing specification tests under test/EFCore.Tests/ChangeTracking/.	fail→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-14 When EF Core compiles property accessors for deeply nested complex collections, how does the accessor determine which collection element to index at each nesting level?	pass→pass	—	—	—	—	—	—	—	—	—	—	—	—
case-15 Which primary method in EF Core performs snapshot comparison across all tracked entities to mark modified properties before SaveChanges()? A developer assumed Update() performs property scanning on every property setter call.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-17 When contributing tests to EF Core, how should developers choose between placing a test in test/EFCore.Tests/ChangeTracking/ versus test/EFCore.Specification.Tests/GraphUpdates/?	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—
case-18 Why does EF Core use PropertyAccessorsFactory during change tracking initialization instead of invoking standard C# delegates via reflection? A developer claimed reflection invocation has zero performance impact.	fail→fail	—	—	—	—	—	—	—	—	—	—	—	—

These cases were also screened by the skill’s intent / safety pass.See the Trust review ↗Reproduce this benchmark in Colab ↗

How this skill was measured

DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted. The headline lift of +18 percentage points is the difference between those two pass rates over the 22 comparable cases.

Model measured: gemini-3.6-flash
Graded by: gemini-3.6-flash
Grading method: judged
Verification: verified
Pass rate without the skill: 9.1%
Pass rate with the skill: 27.3%
Cases attempted: 22
Cases counted toward lift: 22
Cases that regressed: 0
Skill version measured: v1
Run completed: 7/27/2026, 20:18 UTC

The per-case answers from this run were removed by the retention sweep, so the case table below shows the verdicts without the text either arm produced. The counts above were recorded at the time and are unaffected. Answers are now kept for 180 days.

SkillScore blends 4 signals1 of 4 complete

BenchmarkPass rate WITH skill on a verified run27

Live evalNeeds ≥10 evaluated traces in 30 days

AI ratingNeeds ≥10 rated traces

AdoptionNeeds ≥10 serves across ≥2 orgs in 30 days

Efficiency · separate axis (at equal correctness)+0% turns-71% tokens

Shown for transparency; not credited unless a verified run shows no correctness regression.

Backed by 1 of 4 signals — each added signal makes the score more robust.

Verified on gemini-3.6-flash · re-tested 55 days ago

Other measured skills in the registry, with their headline benchmark lift.

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Change Tracking

SkillSafety

Source

Change Tracking

Core Components

Testing

Common Pitfalls

Validation

How this skill was measured

Related skills