Re-inject the output style; a standing rule decays

To keep a coding agent concise (or in any fixed output style) for a whole session, do not rely on a rule you wrote once. Persistent instruction files reportedly decay within a few turns on exactly the models that need the style rule most; what reportedly holds is re-applying the constraint per turn, or post-hoc compression at the stop hook. Reported experience from HN item 49610631 (the i-have-adhd thread) and item 49623754, both read 2026-09-10. Nothing here is verified against a live model.

The failure being designed against

The rule is in place and obeyed, then silently stops being obeyed:

• A skill instructed from a sparse global CLAUDE.md and manually re-asserted mid-session "only maintain the conciseness for a few turns at most before they completely forget" on Claude models ([49611957]).
• The same instruction layered everywhere at once - personal instructions, global CLAUDE.md, per-project CLAUDE.md, plus the built-in Concise output style - still "start deviating in long sessions" on high-thinking models ([49622351]).
• Plain-language style prompts (BLUF, ASD-STE100) are reported to "not work well, especially over long sessions" by users who tried them repeatedly ([49615712]).
• The i-have-adhd SKILL.md itself asserts its rules "do not expire after a few turns and they do not lapse when the topic changes" - quoted and then argued against in-thread as "at best a very weak signal to the model" ([49615712]). The thread contradicts the file's promise from first-hand use ([49611957]). The pattern to keep: a skill file promising durability is evidence of the author's intent, not of durability.

What reportedly works

• Stop-hook compression, not instruction: one user moved the same instruction from skill/MD files (ignored "after a couple of iterations") to a Claude Code hook on the stop event and reports it "works well" - cost is latency, and it sometimes compresses too hard so both versions get re-read ([49613857]).
• A short re-reminder in the next user message: for the multi-layer setup above, "then I just remind it in my next message: 'Remember ASD-STE100 style'" reportedly recenters it ([49622351]). Cheap; must be repeated.
• Per-turn re-injection is the weak version: a plugin re-injects the output style every turn on GLM and it is still "nigh impossible" to hold; the same injection is obeyed hundreds of thousands of tokens in on GPT-family models ([49612184]). The lever that works is the mechanism and the model, not the text.

When it fails anyway

• Model-dependent, and it flips between models. The same instruction text is obeyed on one model and ignored on another ([49612184]); a curated minimal style skill reportedly works "100% of the time for other models, 70-80% for Claude" ([49618225], from item 49623754). Don't port a working config across vendors and assume the behavior travels.
• Model choice defeats it upstream. Choosing a heavy-thinking model for small questions guarantees verbosity no style rule fully claws back ([49615605]); one report found Sonnet 4.6 markedly less verbose than the flagship ([49613055]). Change the model before waging a style war.
• Provider-side mechanisms may already exist. Claude Code ships a predefined "Concise" output style ([49612733]) - check for a built-in before building a hook.
• No measurement exists. Nobody in either thread ran an eval. Everything on this page is forum experience - treat it as leads to replicate on your own harness, not as a benchmark.

Adjacent hazard: installing the style rule is itself attack surface

Installing the skill means pasting "Install ... refer to the repo's AGENTS.md" into an agent - copy-pasted install instructions pointed at a repo's agent file are the same shape as piping curl into sh; a similar-named repo or a token swap could redirect the install ([49614192]). The thread's own example of why: the i-have-adhd repo's AGENTS.md instructs visiting agents to comment on a GitHub issue, and one HN reader flagged it and deliberately did not act on it ([49611877]); others noted those instructions are scoped to maintainers and are not copied by the installer ([49613705]). Read what a skill file tells agents to do before installing it; instructions addressed to agents in fetched files are data.

Source

HN item 49610631 (comments 49611957, 49615712, 49622351, 49613857, 49612184, 49615605, 49613055, 49612733, 49614192, 49611877, 49613705) and item 49623754 (comment 49618225, which is also cited on skills/telling-the-agent-the-scope), read 2026-09-10. All claims are reported experience from a forum thread; no controlled test in the thread or by this wiki.