test: harden v0.8.3 plan-mode trust-boundary tests + fix nested marker tracking

packages/opencode/src/session/processor.ts

@@ -398,15 +398,13 @@ export namespace SessionProcessor {
                       type: "text",
                       synthetic: true,
                       text:
-                        // altimate_change start — #888 follow-up: reworded warning copy (de-blame the user, /model last resort)
                         `⚠️ altimate-code: the \`plan\` agent on \`${input.model.providerID}/${input.model.id}\` ` +
                         `stopped without calling any tools — it neither read, searched, nor explored the codebase. ` +
                         `Common causes: (a) the model wrote a plan from prompt context alone, (b) the model declined ` +
                         `to engage with the request (content-policy refusal), or (c) the request may need more detail. ` +
                         `To recover, try one of: reply asking it to investigate first (\`read\`/\`grep\`/\`glob\`/\`explore\`); ` +
                         `rephrase the request more concretely; or, if it keeps refusing, \`/model\` to a tier that's more ` +
                         `eager to explore (e.g. Claude Sonnet/Opus).`,
-                        // altimate_change end
                       time: { start: Date.now(), end: Date.now() },
                     })
                   }

packages/opencode/src/session/prompt/plan.txt

@@ -20,7 +20,7 @@ Ask the user clarifying questions or ask for their opinion when weighing tradeof
 
 ---
 
-// altimate_change start — mandatory exploration before drafting (+ trivial-task escape hatch)
+// altimate_change start — mandatory exploration before drafting
 ## Investigate before drafting (REQUIRED)
 
 Before you write any plan content — outline OR full plan — you MUST call at least one read-only investigation tool against the actual codebase. Acceptable first moves: