CLAUDE_AUTOCOMPACT_PCT_OVERRIDE in settings.json env block silently ignored by autocompact logic

[rasatpetabit]

Bug

Setting CLAUDE_AUTOCOMPACT_PCT_OVERRIDE in the env block of settings.json has no effect on the autocompact threshold. The variable is visible to subprocess tool calls (e.g. Bash) but is not applied to the Claude Code application's own autocompact logic.

Steps to reproduce

1. Add "CLAUDE_AUTOCOMPACT_PCT_OVERRIDE": "75" to the env section of ~/.claude/settings.json
2. Start a long session until context exceeds 75%
3. Observe: autocompact does not fire
4. Run Bash(echo $CLAUDE_AUTOCOMPACT_PCT_OVERRIDE) — confirms subprocess sees 75
5. Session continues past 86% with no autocompact trigger

Expected behavior

Either:

• The env block in settings.json should apply to app-level configuration knobs (including autocompact threshold), not only to subprocess invocations, OR
• The docs/settings UI should clearly distinguish between "subprocess env vars" and "app configuration vars" and provide a separate mechanism for the latter

Actual behavior

Autocompact threshold is not respected. The only workaround is to export the variable in the shell before launching Claude Code (export CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=75 in .bashrc/.zshrc).

Environment

• Claude Code CLI (headless Linux server)
• Model: claude-sonnet-4-6
• settings.json env injection confirmed working for subprocess calls
• Context reached 86% (172.6k/200k) without autocompact firing despite threshold set to 75%

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=50 does not trigger autocompact — context reaches 100% requiring manual /compact #52390
2. [Bug] Auto-Compact not triggering with CLAUDE_AUTOCOMPACT_PCT_OVERRIDE setting #57627
3. [Bug] Auto-compact triggers at 16% despite CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=30 set #53358

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🤖 Generated with Claude Code

[ryota-murakami]

Reproducible on v2.1.156 / macOS (darwin, Apple Silicon) / claude-opus-4-8 as well — broadening this beyond the Linux/Sonnet report.

Setup (~/.claude/settings.json env block):

"CLAUDE_AUTOCOMPACT_PCT_OVERRIDE": "83",  // also tried "70" and "90"
"CLAUDE_CODE_DISABLE_1M_CONTEXT":  "1"

Repro step 4 confirmed — a Bash subprocess does see the value:

$ echo $CLAUDE_AUTOCOMPACT_PCT_OVERRIDE
90

So the var is injected into the process env, but the app's own autocompact logic never acts on it.

What we saw: /context reported 221.8k / 200k (111%) and autocompact never fired, despite the override sitting far below that line. Manual /compact works.

Likely compounding cause specific to Opus 4.8 / 1M models: even with CLAUDE_CODE_DISABLE_1M_CONTEXT=1 set, the session appears to be evaluated against the 1M window (Opus 4.8's default), so 221.8k is only ~22% of the effective window — below any threshold. That makes the override look "ignored" and keeps the trigger from ever arriving. Consistent with #34143 / #35677 (Opus reported as 200K while effectively on 1M) and #43989 (threshold computed against the large window).

So from the user's seat it's two overlapping failures: (1) the env-block PCT_OVERRIDE is not applied to the app's own autocompact logic (this issue), and (2) on Opus 4.8 the effective window stays 1M regardless of DISABLE_1M_CONTEXT, so the percentage never climbs to the trigger line even when raw tokens exceed 200k.

Please keep this open — still reproducible on v2.1.156.

[dalilion]

Also reproducible on Claude Code 2.1.178 inside the Cursor / VS Code extension (CLAUDE_CODE_ENTRYPOINT=claude-vscode), macOS (Apple Silicon), claude-opus-4-8 [1m] — extending this beyond the headless-CLI / Sonnet reports to the IDE-extension surface.

Same signature: the variable is present in the process env (a Bash tool call echoes CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=50 correctly), but the app's auto-compact logic ignores it and only fires at the built-in ~90% default. At ~70% context used the status UI still shows "21% of context remaining until auto-compact."

Important wrinkle for IDE users: the .bashrc / .zshrc shell-export workaround does not help the Cursor / VS Code extension. It's GUI-launched and doesn't inherit interactive-shell rc files, so the extension host's process env never receives the export. Combined with the settings.json env-block path being ignored by the app logic (this issue), there is currently no working way to set the threshold in the extension at all — only the on/off autoCompactEnabled.

Possible regression marker: on the same machine the PATH CLI reports claude --version → 2.1.71 while the running extension is 2.1.178. This matches the "it worked, then suddenly stopped after an update" pattern several reporters here describe.

A first-class autoCompactThresholdPercent key in settings.json (parallel to autoCompactEnabled), read by the app's own config layer rather than via the subprocess env block, would resolve this cleanly for both the CLI and the IDE extensions.

[AgainPsychoX]

I hate that this and many other long known issues are not fixed, but silently closed, like #53801 (one of few duplicates of current issue). Anthropic never cares :/