fix(opencode): fix 1M context for Opus - compaction token counting (#154)

.opencode/command/upstream-gap.md

@@ -0,0 +1,48 @@
+---
+description: "Analyze gap between our fork and upstream opencode"
+---
+
+## Upstream Gap Analysis
+
+You are the project manager for the opencode fork at `randomm/opencode`. Analyze the gap between our fork's `dev` branch and the upstream `anomalyco/opencode` `dev` branch.
+
+### Steps
+
+1. **Fetch upstream:**
+   !`git fetch anomalyco 2>&1 || echo "Add remote first: git remote add anomalyco git@github.com:anomalyco/opencode.git"`
+
+2. **Get the divergence point:**
+   !`git merge-base dev anomalyco/dev`
+
+3. **List upstream commits we don't have** (grouped by date):
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/ | head -80`
+
+4. **Count by area:**
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/provider/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/session/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/tool/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/agent/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/config/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/mcp/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/opencode/src/permission/ | wc -l`
+   !`git log --oneline --no-merges anomalyco/dev --not dev -- packages/sdk/ | wc -l`
+
+5. **Our fork's unique changes** (not in upstream):
+   !`git log --oneline --no-merges dev --not anomalyco/dev -- packages/opencode/ | head -40`
+
+### Analysis Instructions
+
+Based on the above data:
+
+1. **Create a summary table** of upstream changes grouped by area, with commit count and description of what changed
+2. **Flag conflicts** - identify areas where BOTH our fork AND upstream made changes (these need careful 3-way merge)
+3. **Recommend priority** - rank which upstream changes are most valuable to port:
+   - CRITICAL: Security fixes, major bug fixes
+   - HIGH: New features we need (e.g., SDK upgrades, new providers)
+   - MEDIUM: Improvements and refactors
+   - LOW: Minor fixes, cosmetic changes
+4. **Note already ported** - identify any upstream changes we already manually ported
+
+Present the results and ask the user which items they want to port.
+
+$ARGUMENTS

packages/opencode/src/provider/provider.ts

@@ -638,6 +638,12 @@ export namespace Provider {
       variants: {},
     }
 
+    // Override context limit for Anthropic models with context-1m header support
+    // The models.dev API returns 200k for these models, but with our context-1m header they support 1M
+    if (provider.id === "anthropic" && (m.id.startsWith("claude-sonnet-") || m.id.startsWith("claude-opus-4"))) {
+      m.limit.context = 1_000_000
+    }
+
     m.variants = mapValues(ProviderTransform.variants(m), (v) => v)
 
     return m

packages/opencode/src/session/compaction.ts

@@ -32,7 +32,7 @@ export namespace SessionCompaction {
     if (config.compaction?.auto === false) return false
     const context = input.model.limit.context
     if (context === 0) return false
-    const count = input.tokens.input + input.tokens.cache.read + input.tokens.output
+    const count = input.tokens.input + input.tokens.cache.read
     const output = Math.min(input.model.limit.output, SessionPrompt.OUTPUT_TOKEN_MAX) || SessionPrompt.OUTPUT_TOKEN_MAX
     const usable = input.model.limit.input || context - output
     return count > usable

packages/opencode/test/session/compaction.test.ts

@@ -70,7 +70,8 @@ describe("session.compaction.isOverflow", () => {
       directory: tmp.path,
       fn: async () => {
         const model = createModel({ context: 100_000, output: 32_000 })
-        const tokens = { input: 50_000, output: 10_000, reasoning: 0, cache: { read: 10_000, write: 0 } }
+        // Usable = 100k - 32k = 68k. Input + cache.read = 60k + 10k = 70k > 68k
+        const tokens = { input: 60_000, output: 10_000, reasoning: 0, cache: { read: 10_000, write: 0 } }
         expect(await SessionCompaction.isOverflow({ tokens, model })).toBe(true)
       },
     })