CB-523 (opencode): generated worker config pins compaction.auto

A worker that exhausts its context dies mid-turn and its bridge_reply — the whole point of the turn — dies with it. Auto-compaction is a condition of the turn contract for a spawned peer, not an operator preference. OPENCODE_CONFIG is merged over ~/.config/opencode/config.json rather than replacing it, so workers already inherited auto:true from the home file. That inheritance is exactly what this removes as a dependency: the home file is outside this repo, differs per machine, and is not ours to rely on. The trade is recorded in the code: an OPENCODE_CONFIG value overrides the home value, so an operator cannot disable compaction for bridged workers from home. Deliberate for peers we spawn and whose turns we must land; per-profile control would be a profile knob, not the removal of this line. Origin: fleet-wide auto-compaction audit by peer lead gpt-sol-5.6, which found autoCompactEnabled:false alongside a 300k window across the Claude instance configs. Handed over uncommitted; taken deliberately, with rationale added.
2026-08-13 21:03:46 +02:00
parent f55d3c203b
commit 13ea79f6fd
2 changed files with 17 additions and 0 deletions
@@ -247,6 +247,21 @@ public final class OpenCodeLauncher extends HerdrPeerLauncher {

            ObjectNode root = JSON.createObjectNode();
            root.put("$schema", "https://opencode.ai/config.json");
+            // CB-523, opencode side: a worker that runs out of context dies mid-turn, and its reply
+            // — the entire point of the turn — is lost with it. Auto-compaction is therefore not an
+            // operator preference for a bridged worker, it is a condition of the turn contract.
+            //
+            // Stated deliberately even though it is redundant today: OPENCODE_CONFIG is MERGED over
+            // ~/.config/opencode/config.json rather than replacing it, so a worker already inherits
+            // an `auto: true` set at home. We do not want that inheritance to be what the guarantee
+            // rests on — the home file is outside this repo, differs per machine, and is not ours.
+            //
+            // Know the cost before removing it: this key WINS over the home config (verified — an
+            // OPENCODE_CONFIG value overrides the home value, it does not defer to it), so an
+            // operator who sets `compaction.auto: false` at home cannot turn it off for bridged
+            // workers. That is the intended trade for peers we spawn and whose turns we must land;
+            // if per-profile control is ever wanted, add a profile knob rather than dropping this.
+            root.putObject("compaction").put("auto", true);

            if (cfg.hasMcp()) {
                Path charter = dir.resolve("reply-charter.md");