Andrey Gaag - Field Notes & ArticlesField notes and long-form articles on AI agents, LLM systems, and agent reliability.https://andreygaag.com/enAn API Schema Describes Vendor Intent, Not Client Behaviorhttps://andreygaag.com/notes/2026-08-14-api-schema-describes-vendor-intent/https://andreygaag.com/notes/2026-08-14-api-schema-describes-vendor-intent/A documented hash in a VK button broke mini-app navigation; comparing three links found the cause where another schema-based hypothesis did not.Fri, 14 Aug 2026 00:00:00 GMTA Dynamic Tail in the System Prompt Disables the Provider Cachehttps://andreygaag.com/notes/2026-08-14-dynamic-system-prompt-tail-breaks-cache/https://andreygaag.com/notes/2026-08-14-dynamic-system-prompt-tail-breaks-cache/A timestamp and memory near the start of a 92K-token agent request made every call cold; a stable prefix and cached-token metric made the defect testable.Fri, 14 Aug 2026 00:00:00 GMTCUDA PTX vs. SASS: Toolchain and GPU Architecture Decide Whether the Model Runshttps://andreygaag.com/notes/2026-08-13-cuda-ptx-vs-sass/https://andreygaag.com/notes/2026-08-13-cuda-ptx-vs-sass/Why a fresh llama.cpp build still crashed on Blackwell and how native SASS removed the incompatible PTX JIT path.Thu, 13 Aug 2026 00:00:00 GMTA Stupid Mistake That Broke the Agent's Contexthttps://andreygaag.com/notes/2026-08-10-oldest-images-break-agent-context/https://andreygaag.com/notes/2026-08-10-oldest-images-break-agent-context/A slice taken from the wrong end made a multimodal agent receive the oldest images instead of the newest ones.Mon, 10 Aug 2026 00:00:00 GMTPostgres, Partitions, and Missing Postshttps://andreygaag.com/notes/2026-08-07-insert-rowcount-is-not-a-delivery-signal/https://andreygaag.com/notes/2026-08-07-insert-rowcount-is-not-a-delivery-signal/The data reached its partitions, but cursor.rowcount returned zero and prevented the processing pipeline from starting.Fri, 07 Aug 2026 00:00:00 GMThash() Is Stable Only Within a Single Processhttps://andreygaag.com/notes/2026-08-07-python-hash-is-process-local/https://andreygaag.com/notes/2026-08-07-python-hash-is-process-local/One source generated a new post_id for the same URL on every process start and bypassed deduplication.Fri, 07 Aug 2026 00:00:00 GMTSemantic Decisions Belong to the Model; Critical Invariants to Codehttps://andreygaag.com/notes/2026-08-02-semantic-decisions-model-invariants-code/https://andreygaag.com/notes/2026-08-02-semantic-decisions-model-invariants-code/In an agent system, the model should interpret requests and choose actions while code preserves guarantees, safety, and irreversible invariants.Sun, 02 Aug 2026 00:00:00 GMTCritical Links Should Not Depend on One External Domainhttps://andreygaag.com/notes/2026-07-14-telegram-domain-outage/https://andreygaag.com/notes/2026-07-14-telegram-domain-outage/When an external Telegram domain temporarily stopped working, every link to a bot, channel, or user failed at once.Tue, 14 Jul 2026 00:00:00 GMTDelayed Execution Should Be a Separate Toolhttps://andreygaag.com/notes/2026-07-09-delayed-tool-execution/https://andreygaag.com/notes/2026-07-09-delayed-tool-execution/When scheduling is embedded in every tool, new channels inflate the codebase; a shared scheduling tool keeps that logic in one place.Thu, 09 Jul 2026 00:00:00 GMTJWT Refresh Broke After a Service Migrationhttps://andreygaag.com/notes/2026-07-07-jwt-refresh-mismatch/https://andreygaag.com/notes/2026-07-07-jwt-refresh-mismatch/After a service move, users were logged out because access and refresh tokens became unsynchronized and configuration silently fell back to defaults.Tue, 07 Jul 2026 00:00:00 GMTThe Payment Succeeded, but the Plan Was Not Appliedhttps://andreygaag.com/notes/2026-07-06-payment-without-tariff/https://andreygaag.com/notes/2026-07-06-payment-without-tariff/The payment flow assumed that a plan already existed: update-only logic must create the state when a concurrent trial operation has not created it yet.Mon, 06 Jul 2026 00:00:00 GMTI Ran a Coding Agent on Two Consumer GPUs. Speed Wasn't the Bottleneck.https://andreygaag.com/blog/north-mini-code/https://andreygaag.com/blog/north-mini-code/North Mini Code crossed the usefulness threshold under supervision, but not the trust threshold, on a local two-GPU coding-agent setup.Sun, 05 Jul 2026 00:00:00 GMTLLM Context Is Not a Databasehttps://andreygaag.com/blog/llm-context-is-not-a-database/https://andreygaag.com/blog/llm-context-is-not-a-database/Large tool outputs turn the prompt into an accidental data store; reliable agents keep growing data external, bounded, and retrievable.Sat, 04 Jul 2026 00:00:00 GMTA Client Loop Caused a Threefold Database Connection Spikehttps://andreygaag.com/notes/2026-07-02-database-connection-spike/https://andreygaag.com/notes/2026-07-02-database-connection-spike/Even successful repeated requests can exhaust a connection pool: the server needs rate limits, and the client needs a guard against loops after streaming failures.Thu, 02 Jul 2026 00:00:00 GMTKeep Alembic revision ids under 32 charactershttps://andreygaag.com/notes/2026-06-30-alembic-revision-length/https://andreygaag.com/notes/2026-06-30-alembic-revision-length/Alembic stores the current revision in a VARCHAR(32) column, so long human-authored revision ids overflow and break migrations.Tue, 30 Jun 2026 00:00:00 GMTApp Store Review Exposed Unfinished Product Requirementshttps://andreygaag.com/notes/2026-06-29-app-store-review/https://andreygaag.com/notes/2026-06-29-app-store-review/The iOS rejection showed that technical readiness is not enough without account deletion, appropriate authentication, safe screenshots, and a clear payment model.Mon, 29 Jun 2026 00:00:00 GMTDo Not Share Local and Container Environmentshttps://andreygaag.com/notes/2026-06-17-zed-ruff-environment/https://andreygaag.com/notes/2026-06-17-zed-ruff-environment/Ruff stopped launching in Zed because the local project used a Linux binary from a container virtualenv.Wed, 17 Jun 2026 00:00:00 GMTUnbounded Conversation History Can Exceed the Context Windowhttps://andreygaag.com/notes/2026-06-16-agent-context-compact/https://andreygaag.com/notes/2026-06-16-agent-context-compact/The harness capped retrieved memory but left active conversation history unbounded; recovery after a restart suggested, but did not prove, context overflow.Tue, 16 Jun 2026 00:00:00 GMTUser Data Should Be Soft-Deletedhttps://andreygaag.com/notes/2026-06-11-soft-delete-chats/https://andreygaag.com/notes/2026-06-11-soft-delete-chats/When a user deletes a chat by mistake, soft deletion with controlled recovery is safer than immediate physical deletion.Thu, 11 Jun 2026 00:00:00 GMTThe Canon Has Not Yet Formedhttps://andreygaag.com/blog/agentic-engineering-canon/https://andreygaag.com/blog/agentic-engineering-canon/The engineering discipline of agentic systems is taking shape before our eyes: core computer science principles remain, but the canon of agent engineering does not yet exist.Tue, 09 Jun 2026 00:00:00 GMTQwen3.5:32B and OpenCode Compatibility Is a Contracthttps://andreygaag.com/notes/2026-06-08-opencode-model-compatibility/https://andreygaag.com/notes/2026-06-08-opencode-model-compatibility/A local coding-agent session can stop because of an incompatible reasoning format even after the model loads and changes files successfully.Mon, 08 Jun 2026 00:00:00 GMTCI Should Not Depend on One Package Registryhttps://andreygaag.com/notes/2026-06-08-package-registry-outage/https://andreygaag.com/notes/2026-06-08-package-registry-outage/External PyPI timeouts can break container builds; mirrors and an owned registry turn that dependency into a manageable failure.Mon, 08 Jun 2026 00:00:00 GMTA Corporate Network Can Block SSEhttps://andreygaag.com/notes/2026-06-08-sse-blocked-by-corporate-network/https://andreygaag.com/notes/2026-06-08-sse-blocked-by-corporate-network/Working HTTP requests do not prove that a corporate network allows the long-lived SSE connection required for streaming agent responses.Mon, 08 Jun 2026 00:00:00 GMTDeleting a File Does Not Clear RAG Memoryhttps://andreygaag.com/notes/2026-06-06-agent-rag-memory-cleaning/https://andreygaag.com/notes/2026-06-06-agent-rag-memory-cleaning/Deleting source documents does not guarantee that their vector representations are gone: an agent's memory must be cleared at every storage layer.Sat, 06 Jun 2026 00:00:00 GMTWhy an Agent Should Not Choose the Architecture for an Unfamiliar Taskhttps://andreygaag.com/notes/2026-06-06-agent-voice-cloning/https://andreygaag.com/notes/2026-06-06-agent-voice-cloning/Asking an agent to clone a voice without prior research turned into endless trial and error: define the architecture and evaluation criteria first.Sat, 06 Jun 2026 00:00:00 GMTOne Vision Model Is Not Enough for Reliable Receipt Parsinghttps://andreygaag.com/notes/2026-06-06-receipt-vision-parsing/https://andreygaag.com/notes/2026-06-06-receipt-vision-parsing/A vision model may read a receipt but still confuse prices, names, quantities, or totals; reliability requires a verifiable pipeline.Sat, 06 Jun 2026 00:00:00 GMTAn Audio Fallback Must Cover Real Decode Failureshttps://andreygaag.com/notes/2026-06-01-audio-fallback/https://andreygaag.com/notes/2026-06-01-audio-fallback/Audio files can play successfully while a library fails to inspect them: an ffmpeg fallback should not be limited to one assumed exception type.Mon, 01 Jun 2026 00:00:00 GMTNot Every Good Idea Deserves Automationhttps://andreygaag.com/notes/2026-06-01-automation-needs-a-test/https://andreygaag.com/notes/2026-06-01-automation-needs-a-test/An idea suggested by a model and phrased conveniently is not automatically a useful change: validate its value and success criteria first.Mon, 01 Jun 2026 00:00:00 GMT