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Practical writing about software, systems, and the small details that make products feel solid.

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Fresh from the notebook

Cybersecurity 22 Sep 2026 4 min read

X-Content-Type-Options Blocks MIME Type Sniffing

X-Content-Type-Options Blocks MIME Type Sniffing HTTP responses carry a Content-Type header that describes the media type of the representation. Browsers also have a history of inferring a type from response bytes when the declared type is absent, incorrect, or ambiguous. That inference can be useful for old content, but it creates an execution boundary that application operators may not intend. X-Content-Type-Options: nosniff narrows that boundary. For request destinations covered by the browser’s MIME checking rules, the response must have an acceptable declared type instead of relying on content sniffing. The header is small, but its effect depends on correct Content-Type values throughout the application.

Cybersecurity Web Security

Software Engineering 22 Sep 2026 6 min read

Write Skew Can Break Invariants Under Snapshot Isolation

Write Skew Can Break Invariants Under Snapshot Isolation Snapshot isolation gives each transaction a stable view of committed data and usually rejects concurrent updates to the same row. That combination removes many anomalies that appear under weaker isolation levels. It does not, however, make every application invariant serializable. Write skew is the important edge case. Two transactions read overlapping state, make decisions from the same valid snapshot, then update different rows. Because their write sets do not collide, both can commit. The combined result can violate a rule that neither transaction violated in its own snapshot.

Software Engineering Databases

Software Engineering 22 Sep 2026 6 min read

Transactional Outbox Closes the Database-to-Broker Commit Gap

Transactional Outbox Closes the Database-to-Broker Commit Gap A service often needs one operation to change database state and emit a message. An order may become confirmed while an OrderConfirmed event is sent to a broker. Those actions touch separate systems, so two ordinary writes cannot form one atomic commit unless both systems participate in a distributed transaction. The dangerous part is the interval between the writes. Commit the database first and the process can fail before publishing. Publish first and the database commit can fail afterward. Reversing the order moves the failure window; it does not remove it.

Software Engineering Distributed Systems

Artificial Intelligence 22 Sep 2026 5 min read

Top-p Sampling Rebuilds Its Candidate Set at Every Token

Top-p sampling does not keep a fixed shortlist of tokens throughout generation. At each decoding step, the model produces a new logit vector, that vector becomes a probability distribution, and the sampler forms a new candidate set whose cumulative probability mass reaches the configured threshold. The consequence is easy to miss in serving code: the same top_p value can admit two tokens at one step and dozens at another. The parameter controls probability mass, not candidate count.

Artificial Intelligence Decoding

Software Engineering 22 Sep 2026 6 min read

Tombstones Prevent Deleted Data from Reappearing

Tombstones Prevent Deleted Data from Reappearing Deletion is not merely the absence of a value in a replicated store. Absence carries no information about whether a key was deliberately removed or whether a replica has simply never received it. When replicas can be temporarily disconnected, that distinction determines whether synchronization preserves a deletion or accidentally restores old data. A tombstone records the deletion as versioned state. Replicas can compare that marker with older values and keep the deletion when they reconcile. The marker can eventually be reclaimed, but only after the system has a defensible boundary beyond which an older value cannot return.

Software Engineering Distributed Systems

Linux 22 Sep 2026 5 min read

TFD_TIMER_CANCEL_ON_SET Reports Realtime Clock Discontinuities

A timerfd armed against wall-clock time can cross a discontinuous clock adjustment before its deadline. With TFD_TIMER_CANCEL_ON_SET, Linux exposes that event through the descriptor: a subsequent read() fails with ECANCELED rather than presenting the clock jump as an ordinary timer expiration. The flag is deliberately narrow. It applies only when timerfd_settime() arms an absolute timer on CLOCK_REALTIME or CLOCK_REALTIME_ALARM, and it changes the handling of discontinuous changes to those clocks.

Linux timerfd

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