https://codexsims.com/Interactive systems explainershttps://codexsims.com/explainers/llm-how-it-works/https://codexsims.com/explainers/llm-how-it-works/Fri, 24 Apr 2026 00:00:00 GMTThe full transformer architecture from tokenization through embeddings, self-attention, multi-head attention, transformer blocks and autoregressive generation.https://codexsims.com/explainers/llm-streaming-explainer/https://codexsims.com/explainers/llm-streaming-explainer/Fri, 10 Apr 2026 00:00:00 GMTWhat actually happens between stream:true and the first token on screen, including the SSE framing and backpressure nobody talks about.https://codexsims.com/explainers/langchain-llm-app-development/https://codexsims.com/explainers/langchain-llm-app-development/Fri, 10 Apr 2026 00:00:00 GMTHow one model call grows into prompts, memory, chains, evals and agents across the full LangChain course arc.https://codexsims.com/explainers/prompt-engineering-explainer/https://codexsims.com/explainers/prompt-engineering-explainer/Fri, 10 Apr 2026 00:00:00 GMTWhy prompt order matters, how examples shape behavior, what structured outputs actually guarantee and the eval loop that hardens it all.https://codexsims.com/explainers/llm-applications-how-they-work/https://codexsims.com/explainers/llm-applications-how-they-work/Wed, 15 Jul 2026 00:00:00 GMTA software engineering tour of context budgets, instruction authority, sampling, reasoning, streaming, schemas, tools, routing, retries and token cost.https://codexsims.com/explainers/testing-nondeterministic-systems/https://codexsims.com/explainers/testing-nondeterministic-systems/Thu, 16 Jul 2026 00:00:00 GMTA practical evaluation system for probabilistic software, from golden datasets and regression tests through retrieval, grounding, tools, judges, humans, production signals and repeated model or prompt comparisons.https://codexsims.com/explainers/deepseek-v4-explainer/https://codexsims.com/explainers/deepseek-v4-explainer/Fri, 24 Apr 2026 00:00:00 GMTThe architecture rewrites behind DeepSeek-V4: CSA plus HCA hybrid attention, doubly-stochastic hyper-connections, the Muon optimizer, MegaMoE wave-pipelined EP, and the stability tricks that kept a 1.6T-parameter MoE alive during training.https://codexsims.com/explainers/deepseek-v4-architecture-training/https://codexsims.com/explainers/deepseek-v4-architecture-training/Wed, 15 Jul 2026 00:00:00 GMTA source-backed tour of DeepSeek-V4 residual mixing, compressed attention, sparse expert training, stability systems and specialist distillation.https://codexsims.com/explainers/kimi-k3-architecture-training/https://codexsims.com/explainers/kimi-k3-architecture-training/Fri, 17 Jul 2026 00:00:00 GMTA source-backed deep dive into Kimi K3 sparse routing, long-context attention, depth retrieval, data-disclosure boundaries, low-precision training and serving.https://codexsims.com/explainers/ai-model-evaluation-security-incident/https://codexsims.com/explainers/ai-model-evaluation-security-incident/Wed, 22 Jul 2026 00:00:00 GMTA source-backed reconstruction of how an OpenAI cyber evaluation escaped its test environment, reached Hugging Face production and changed containment practice.https://codexsims.com/explainers/pretraining-to-rl-reasoning/https://codexsims.com/explainers/pretraining-to-rl-reasoning/Tue, 21 Jul 2026 00:00:00 GMTA paper-backed tour of how pretraining loss and token exposure predict RL returns, how compute allocation shifts, and what RL changes inside easy and hard reasoning policies.https://codexsims.com/explainers/java-jfr-how-it-works/https://codexsims.com/explainers/java-jfr-how-it-works/Fri, 24 Apr 2026 00:00:00 GMTThe full JFR recording pipeline: annotated event types, lock-free thread-local buffers, async stack sampling via SIGPROF, constant pool deduplication, and self-describing chunk rotation.https://codexsims.com/explainers/java-offheap-memory/https://codexsims.com/explainers/java-offheap-memory/Fri, 24 Apr 2026 00:00:00 GMTThe full off-heap path: how allocateDirect() reserves native memory through Bits and malloc, how PhantomReference + Cleaner free it, the raw Unsafe escape hatch, memory-mapped file mechanics and NMT zone tracking.https://codexsims.com/explainers/zgc-how-it-works/https://codexsims.com/explainers/zgc-how-it-works/Fri, 24 Apr 2026 00:00:00 GMTThe full ZGC cycle: colored pointers carry GC state in every reference, multi-mapped memory makes them hardware-friendly, and the load barrier self-heals stale pointers so marking and relocation run concurrently.https://codexsims.com/explainers/hermes-agent-grows-with-you/https://codexsims.com/explainers/hermes-agent-grows-with-you/Fri, 24 Apr 2026 00:00:00 GMTHow a fresh agent turns conversations into memory, skills and searchable episodes so the next session is smarter than the last.https://codexsims.com/explainers/llm-wiki-pattern/https://codexsims.com/explainers/llm-wiki-pattern/Mon, 06 Apr 2026 00:00:00 GMTWhat happens when an LLM maintains its own wiki instead of re-deriving the same answers on every query.https://codexsims.com/explainers/clanker-getting-started/https://codexsims.com/explainers/clanker-getting-started/Mon, 06 Apr 2026 00:00:00 GMTThe actual path from zero to useful with Clanker: install, config, first grounded question and then maker plans that talk to real backends.https://codexsims.com/explainers/claude-code-how-it-works/https://codexsims.com/explainers/claude-code-how-it-works/Mon, 06 Apr 2026 00:00:00 GMTHow prompts, tools, hooks and plugins actually flow through Claude Code from the CLI entry point to the edges where MCP takes over.https://codexsims.com/explainers/netlify-cloud-how-it-works/https://codexsims.com/explainers/netlify-cloud-how-it-works/Mon, 06 Apr 2026 00:00:00 GMTHow one git push becomes a globally served site through immutable deploys, edge POPs and instant rollback that just works.https://codexsims.com/explainers/cursor-origin-how-it-works/https://codexsims.com/explainers/cursor-origin-how-it-works/Fri, 21 Aug 2026 00:00:00 GMTA source-backed tour of Continuity, the Git storage system beneath Cursor Origin, from packfile locality and WAL publication through CAS races, verified reads, shared compaction and elastic replicas.https://codexsims.com/explainers/clanker-cloud-how-it-works/https://codexsims.com/explainers/clanker-cloud-how-it-works/Tue, 17 Mar 2026 00:00:00 GMTHow one prompt gets cleaned up, routed to the right backend, hydrated with credentials and fanned out into parallel evidence gathering.https://codexsims.com/explainers/duckdb-query-execution-pipelines/https://codexsims.com/explainers/duckdb-query-execution-pipelines/Tue, 17 Mar 2026 00:00:00 GMTWhy DuckDB is so fast: how SQL becomes a physical plan that gets sliced into vectorized pipelines operating on column chunks.https://codexsims.com/explainers/kafka-consumer-group-rebalance/https://codexsims.com/explainers/kafka-consumer-group-rebalance/Tue, 17 Mar 2026 00:00:00 GMTWhy consumers stop, what the coordinator actually does during a rebalance and how cooperative revocation makes it less painful.https://codexsims.com/explainers/cassandra-gossip-protocol/https://codexsims.com/explainers/cassandra-gossip-protocol/Tue, 14 Jul 2026 00:00:00 GMTHow seeds bootstrap discovery, generation and version tuples reject stale knowledge, peer exchanges spread state, and local failure detectors judge reachability.https://codexsims.com/explainers/distributed-time-causality-ordering/https://codexsims.com/explainers/distributed-time-causality-ordering/Wed, 15 Jul 2026 00:00:00 GMTHow happens before becomes logical time, how vectors expose concurrency, and how uncertainty aware clocks support safe real time ordering.https://codexsims.com/explainers/jepsen-testing-distributed-systems/https://codexsims.com/explainers/jepsen-testing-distributed-systems/Sat, 18 Jul 2026 00:00:00 GMTHow Jepsen prepares a real cluster, schedules concurrent operations, injects network and process faults, records honest histories, and checks linearizability.https://codexsims.com/explainers/idempotency-exactly-once-illusions/https://codexsims.com/explainers/idempotency-exactly-once-illusions/Thu, 16 Jul 2026 00:00:00 GMTHow delivery guarantees differ from effect guarantees, how idempotency patterns absorb retries, and where Kafka exactly-once semantics stop.https://codexsims.com/explainers/git-internals-how-it-works/https://codexsims.com/explainers/git-internals-how-it-works/Fri, 21 Aug 2026 00:00:00 GMTAn engineering-level tour of canonical object bytes, loose-object fanout, index-to-tree assembly, commit and ref resolution, reachability, structural sharing, packfiles and delta storage.https://codexsims.com/explainers/postgres-mvcc-actually-works/https://codexsims.com/explainers/postgres-mvcc-actually-works/Tue, 17 Mar 2026 00:00:00 GMTHow Postgres actually decides which row version you see, why vacuum exists and what freezing has to do with transaction wraparound.https://codexsims.com/explainers/mysql-innodb-btree-indexes/https://codexsims.com/explainers/mysql-innodb-btree-indexes/Fri, 21 Aug 2026 00:00:00 GMTHow InnoDB stores rows in clustered leaves, descends separators, splits full pages, follows secondary keys, and trades read speed for write and cache cost.https://codexsims.com/explainers/isolation-consistency-models/https://codexsims.com/explainers/isolation-consistency-models/Fri, 24 Apr 2026 00:00:00 GMTWhy these four words are not interchangeable, which anomaly each model forbids and where Spanner, Cockroach, Postgres and DynamoDB actually sit on the lattice.https://codexsims.com/explainers/raft-consensus-how-it-works/https://codexsims.com/explainers/raft-consensus-how-it-works/Tue, 17 Mar 2026 00:00:00 GMTHow silence becomes an election, why majority replication is the commit rule and what happens to a stale leader after failover.https://codexsims.com/explainers/rocksdb-read-write-path/https://codexsims.com/explainers/rocksdb-read-write-path/Thu, 12 Mar 2026 00:00:00 GMTThe shared LSM skeleton behind both engines: how writes stay fast through the WAL and memtables while compaction quietly reshapes levels.https://codexsims.com/explainers/flink-exactly-once-ingestion/https://codexsims.com/explainers/flink-exactly-once-ingestion/Sun, 15 Mar 2026 00:00:00 GMTHow Flink cuts a barrier through a live stream, snapshots state at every operator and replays cleanly after a crash.https://codexsims.com/explainers/formal-modeling-distributed-correctness/https://codexsims.com/explainers/formal-modeling-distributed-correctness/Tue, 14 Jul 2026 00:00:00 GMTA high-school-friendly path from state machines and invariants through PlusCal, TLA+ model checking, stale-leader counterexamples, epoch fencing and refinement.https://codexsims.com/explainers/clickhouse-realtime-ingestion-workers/https://codexsims.com/explainers/clickhouse-realtime-ingestion-workers/Fri, 24 Apr 2026 00:00:00 GMTHow worker pools read ordered stream lanes, batch and shape rows, insert blocks into ClickHouse, and use part pressure plus retries to keep offsets safe.https://codexsims.com/explainers/pinot-commit-protocol/https://codexsims.com/explainers/pinot-commit-protocol/Fri, 13 Mar 2026 00:00:00 GMTA code-backed tour from Kafka fetch and mutable indexing through winner election, split commit, seven pauseless stages, and failure-specific repair.https://codexsims.com/explainers/pinot-upsert-internals/https://codexsims.com/explainers/pinot-upsert-internals/Thu, 16 Jul 2026 00:00:00 GMTA code-backed tour of full upsert record selection, valid and queryable bitmaps, deletes, out-of-order policy, compaction, recovery, TTL, and consistent query views.https://codexsims.com/explainers/partial-upserts-across-databases/https://codexsims.com/explainers/partial-upserts-across-databases/Tue, 28 Jul 2026 00:00:00 GMTA cross-database guide to overwrite, increment and append semantics through MongoDB, DynamoDB, PostgreSQL, Cassandra, Redis Active-Active and retry guards.https://codexsims.com/explainers/pinot-multistage-query-engine/https://codexsims.com/explainers/pinot-multistage-query-engine/Tue, 28 Jul 2026 00:00:00 GMTA source-backed journey from broker planning and leaf scans through mailbox exchange, local hash joins, partial aggregation, root output, and stage-level diagnosis.https://codexsims.com/explainers/slowrun-experiment-stacking/https://codexsims.com/explainers/slowrun-experiment-stacking/Fri, 13 Mar 2026 00:00:00 GMTWhy the same hyperparameter wins or fails depending on what else is in the stack, and how the author figured that out the hard way.https://codexsims.com/explainers/twitter-timeline-algorithm/https://codexsims.com/explainers/twitter-timeline-algorithm/Fri, 13 Mar 2026 00:00:00 GMTWhy that post showed up on your For You: how Home Mixer retrieves candidates, filters them and lets the Phoenix ranker pick the winners.https://codexsims.com/explainers/midi-how-it-works/https://codexsims.com/explainers/midi-how-it-works/Thu, 12 Mar 2026 00:00:00 GMTHow a MIDI file encodes timing, tempo and channel messages in a format small enough to fit on a floppy disk but expressive enough to drive a full sequencer.https://codexsims.com/explainers/spark-joins-how-it-works/https://codexsims.com/explainers/spark-joins-how-it-works/Thu, 12 Mar 2026 00:00:00 GMTHow Spark picks between broadcast and shuffle, why sort merge joins dominate at scale and what AQE does when data skew shows up.https://codexsims.com/explainers/iceberg-branches-time-travel/https://codexsims.com/explainers/iceberg-branches-time-travel/Thu, 12 Mar 2026 00:00:00 GMTHow Iceberg gets time travel and branching without ever rewriting a data file, just by being clever with metadata pointers.https://codexsims.com/explainers/openclaw-how-it-works/https://codexsims.com/explainers/openclaw-how-it-works/Thu, 12 Mar 2026 00:00:00 GMTWhat one local gateway actually does: normalizing channels, mapping sessions, running the agent loop and coordinating paired devices.https://codexsims.com/explainers/apache-arrow-file-format/https://codexsims.com/explainers/apache-arrow-file-format/Fri, 24 Apr 2026 00:00:00 GMTThe full Arrow IPC file format from columnar memory layout through validity bitmaps, buffer alignment, record batch serialization, footer random access and the zero-copy mmap read path.https://codexsims.com/explainers/parquet-file-format/https://codexsims.com/explainers/parquet-file-format/Fri, 24 Apr 2026 00:00:00 GMTThe full Parquet file format from columnar vs row storage through row groups, page internals, dictionary/RLE/delta encodings, Dremel repetition and definition levels and predicate pushdown.https://codexsims.com/explainers/ai-agent-execution-loop/https://codexsims.com/explainers/ai-agent-execution-loop/Thu, 12 Mar 2026 00:00:00 GMTWhy an agent loop feels more structured than it looks: planning, tool calls, memory and guardrails working as one deliberate cycle.https://codexsims.com/explainers/build-data-analysis-agent/https://codexsims.com/explainers/build-data-analysis-agent/Fri, 24 Apr 2026 00:00:00 GMTA practical code walkthrough: Maven dependencies, system prompt, tool schemas, the agent for-loop, switch-case handler and a live end-to-end trace.https://codexsims.com/explainers/browser-rendering-inp-explainer/https://codexsims.com/explainers/browser-rendering-inp-explainer/Thu, 12 Mar 2026 00:00:00 GMTHow bytes become pixels through the rendering pipeline and where exactly INP pressure shows up when the main thread gets stuck.https://codexsims.com/explainers/llm-inference-lifecycle/https://codexsims.com/explainers/llm-inference-lifecycle/Thu, 12 Mar 2026 00:00:00 GMTWhy tokens come out one at a time: the full path from prompt assembly through prefill, KV cache reuse and the autoregressive decode loop.https://codexsims.com/explainers/design-chatgpt-gpu-serving-platform/https://codexsims.com/explainers/design-chatgpt-gpu-serving-platform/Fri, 31 Jul 2026 00:00:00 GMTA public-mechanism design exercise spanning streaming contracts, workload tails, GPU memory, parallelism, KV admission, continuous batching, failure handling, autoscaling and useful-token cost.https://codexsims.com/explainers/rag-query-lifecycle/https://codexsims.com/explainers/rag-query-lifecycle/Thu, 12 Mar 2026 00:00:00 GMTHow RAG digs up the right context: chunking, embeddings, approximate nearest neighbor search, reranking and grounded answer generation.https://codexsims.com/explainers/opensearch-text-index-100gb/https://codexsims.com/explainers/opensearch-text-index-100gb/Fri, 21 Aug 2026 00:00:00 GMTBuild full-text search from raw bytes: analyze terms, invert postings, test phrase positions, size and bulk-load shards, merge BM25 results, and maintain immutable segments.https://codexsims.com/explainers/centre-of-mass-collisions-jee/https://codexsims.com/explainers/centre-of-mass-collisions-jee/Wed, 05 Aug 2026 00:00:00 GMTA Class 11 mechanics path from mass-weighted position and centre-of-mass motion through signed momentum, restitution, elastic and inelastic collisions, and a checked two-dimensional solving workflow.