core LLM completion layer by shaj13 · Pull Request #2443 · docker/docker-agent

shaj13 · 2026-04-15T22:06:02Z

Add new pkg/ai package that extracts and centralizes model interaction logic from runtime.

Add new pkg/ai package that extracts and centralizes model interaction logic from runtime. The package reuses existing types from chat, tools, and provider packages without moving them.

shaj13 · 2026-04-15T22:29:39Z

@dgageot mind taking a look ? Extracted the LLM interaction logic from pkg/runtime and other packages into a new reusable pkg/ai package. This includes streaming, fallback handling, retry, and tool execution — enabling consistent model communication across the codebase. The package is also can be used as a standalone Go library without requiring the full agent runtime.

shaj13 · 2026-04-21T13:02:56Z

@dgageot just a gentle reminder — any update on this PR ?

aheritier

Good refactoring — the pkg/ai package has a clean API, proper separation of concerns, and solid test coverage with golden files. The interceptor pattern is well designed.

A few items need attention before merge:

Merge conflicts — branch is in a dirty state, needs rebase.
WithRetries semantics mismatch — doc says "n + 1 attempts" but code gives exactly n (see inline).
Token usage accumulation bug — loses data when r.Usage != nil && r2.Usage == nil (see inline).
Unguarded slices.IndexFunc result — can panic if model ID not found (see inline).
Cooldown behavior change — the old code only set cooldown when the primary failed with a non-retryable error; the new code always sets cooldown when any fallback succeeds. This is a semantic change that may cause undesired pinning after transient retryable failures exhaust retries.

CI is green on the last push (lint, test, build all pass).

aheritier · 2026-05-06T21:13:40Z

/review

aheritier

Inline comments attached.

aheritier · 2026-05-06T21:13:43Z

+// errors (5xx, timeouts). The total attempts per model is n + 1.
+func WithRetries(n int) Option {
+	return func(c *completion) {
+		c.retries = n


Blocking: The doc says "The total attempts per model is n + 1" but the code uses for retry := range c.retries which yields exactly n iterations. WithRetries(3) = 3 attempts, not 4.

Either fix the doc to "The total attempts per model is n" or change the loop to range c.retries + 1.

aheritier · 2026-05-06T21:13:51Z

+
+	if r2.Usage != nil && r.Usage != nil {
+		r2.Usage = &chat.Usage{
+			InputTokens:       r.Usage.InputTokens + r2.Usage.InputTokens,
+			OutputTokens:      r.Usage.OutputTokens + r2.Usage.OutputTokens,
+			CachedInputTokens: r.Usage.CachedInputTokens + r2.Usage.CachedInputTokens,
+			CacheWriteTokens:  r.Usage.CacheWriteTokens + r2.Usage.CacheWriteTokens,
+			ReasoningTokens:   r.Usage.ReasoningTokens + r2.Usage.ReasoningTokens,
+		}
+	}
+
+	return r2, nil
+}


Non-blocking: If r.Usage != nil but r2.Usage == nil (provider didn't return usage on the recursive call), the first call's token counts are silently lost. Consider:

switch { case r2.Usage != nil && r.Usage != nil: r2.Usage = &chat.Usage{ InputTokens: r.Usage.InputTokens + r2.Usage.InputTokens, OutputTokens: r.Usage.OutputTokens + r2.Usage.OutputTokens, CachedInputTokens: r.Usage.CachedInputTokens + r2.Usage.CachedInputTokens, CacheWriteTokens: r.Usage.CacheWriteTokens + r2.Usage.CacheWriteTokens, ReasoningTokens: r.Usage.ReasoningTokens + r2.Usage.ReasoningTokens, } case r2.Usage == nil && r.Usage != nil: r2.Usage = r.Usage }

aheritier · 2026-05-06T21:13:59Z

+		})
+
+		// Rotate to put the responding model first.
+		c.models = append(c.models[idx:], c.models[:idx]...)
+	}
+
+	r2, err := c.generate(ctx)


Non-blocking: slices.IndexFunc returns -1 when no match is found. If r.Model doesn't match any entry in c.models (e.g. a router provider exposing a different sub-model ID), this will panic on c.models[-1:].

Add a guard:

idx := slices.IndexFunc(c.models, func(m provider.Provider) bool { return m.ID() == r.Model }) if idx > 0 { c.models = append(c.models[idx:], c.models[:idx]...) }

aheritier · 2026-05-06T21:14:09Z

+	for _, m := range models {
+		if m.ID() == res.Model {
+			usedModel = m
+			break
 		}
-		return retryDecisionContinue
 	}

-	if !retryable {
-		slog.Error("Non-retryable error from model",
-			"agent", a.Name(),
-			"model", modelEntry.provider.ID(),
-			"error", err)
-		if !modelEntry.isFallback {
-			*primaryFailedWithNonRetryable = true
+	// Handle cooldown state based on which model succeeded


Question: This now unconditionally sets cooldown whenever a fallback succeeds. The old code only set cooldown when primaryFailedWithNonRetryable was true (429 or 4xx). If the primary exhausts retries on transient 5xx errors and a fallback picks up, the runtime will now pin to that fallback for the full cooldown window — previously it wouldn't.

Is this intentional? If so, it's probably fine (simpler), but worth noting as a behavior change. If not, pkg/ai would need to surface why the fallback was triggered (non-retryable vs exhausted retries).

aheritier · 2026-05-06T21:14:17Z

+		models = append(models, titleModel)
 	}

-	if lastErr != nil {
-		return "", fmt.Errorf("generating title failed: %w", lastErr)
+	str, err := ai.GenerateText(
+		ctx,
+		ai.WithModels(models...),
+		ai.WithMessages(messages...),
+		ai.WithRequireContent(),
+		ai.WithLogger(lg),
+	)
+	if err != nil {
+		return "", fmt.Errorf("generating title failed: %w", err)
 	}
-	return "", nil
+


Praise: Nice simplification of the title generator. The old manual stream-drain + per-model retry loop collapses cleanly into a single ai.GenerateText call with WithRequireContent.

docker-agent

Assessment: 🔴 CRITICAL

1 high-severity panic + 4 medium-severity findings in new pkg/ai completion layer. See inline comments for details.

docker-agent · 2026-05-06T21:19:19Z

+	c.messages = append(c.messages, msgs...)
+
+	if c.models[0].ID() != r.Model {
+		idx := slices.IndexFunc(c.models, func(m provider.Provider) bool {


[HIGH] Panic: slices.IndexFunc result not checked for -1 before use as slice index

slices.IndexFunc returns -1 when no element matches. If r.Model is not found in c.models (e.g., the provider returns an unexpected model ID), idx will be -1 and c.models[-1:] will panic with an index out of range.

The outer if c.models[0].ID() != r.Model guard only checks that the responding model is not the first one — it does not guarantee the model exists anywhere in the slice.

Fix: check idx before use:

idx := slices.IndexFunc(c.models, func(m provider.Provider) bool { return m.ID() == r.Model }) if idx < 0 { idx = 0 // responding model not found; keep current order } c.models = append(c.models[idx:], c.models[:idx]...)

docker-agent · 2026-05-06T21:19:19Z

+			}
+
+			if ctx.Err() != nil {
+				return nil, err


[MEDIUM] Context cancellation returns stream error instead of ctx.Err(), masking cancellation

When ctx.Err() != nil (context was cancelled or timed out), the code returns err — the stream/model error — rather than ctx.Err(). Callers that check errors.Is(err, context.Canceled) or errors.Is(err, context.DeadlineExceeded) will not recognize this as a cancellation and may incorrectly retry or log it as a transient failure.

Note: the select at the bottom of the retry loop (the case <-ctx.Done() branch) correctly returns ctx.Err(), making this path inconsistent.

Fix:

if ctx.Err() != nil { return nil, ctx.Err() // return the cancellation error, not the stream error }

docker-agent · 2026-05-06T21:19:19Z

+			c.onModelFallback(c.models[i-1], model, err)
+		}
+
+		for retry := range c.retries {


[MEDIUM] Off-by-one in retry loop: for retry := range c.retries gives c.retries attempts, not c.retries + 1 as documented

The WithRetries option docs say:

The total attempts per model is n + 1.

But for retry := range c.retries (Go 1.22+ range-over-integer) iterates from 0 to c.retries-1, producing exactly c.retries total attempts — one fewer than documented.

Examples:

WithRetries(1) → 1 attempt (expected: 2)

WithRetries(2) → 2 attempts (expected: 3)

Default (c.retries = 1) → 1 attempt total, meaning zero retries on failure

Fix — change the loop to iterate c.retries + 1 times:

for retry := range c.retries + 1 { ... }

Or update the docs to state "n total attempts" if single-attempt behavior is intentional.

docker-agent · 2026-05-06T21:19:19Z

+			// Handle tool call deltas
+			if len(choice.Delta.ToolCalls) > 0 {
+				for _, delta := range choice.Delta.ToolCalls {
+					idx, ok := toolCallIndex[delta.ID]


[MEDIUM] Empty-string tool call ID used as map key, merging distinct tool calls from streaming providers

toolCallIndex[delta.ID] uses delta.ID directly as a map key. In many streaming LLM protocols, the tool call ID is only sent in the first delta chunk — subsequent delta chunks for the same tool call arrive with delta.ID == "". This is fine for a single tool call per stream.

However, if a streaming provider sends multiple new tool calls where more than one arrives with delta.ID == "" (or a provider that never sends IDs in deltas), all of them are grouped under the same empty-string key. The second new call overwrites the first call's entry in toolCallIndex, and their arguments get merged into a single garbled ToolCall.

Consider adding a guard or using the delta's Index field (if available from the streaming spec) as the map key:

// Use index as primary key, fall back to ID key := fmt.Sprintf("%d", delta.Index) if delta.ID != "" { key = delta.ID } idx, ok := toolCallIndex[key]

Or at minimum validate that new entries (where !ok) have a non-empty ID, and log a warning otherwise.

docker-agent · 2026-05-06T21:19:19Z

-
-		slog.Debug("Generated session title", "session_id", sessionID, "title", result, "model", baseModel.ID())
-		return result, nil
+		models = append(models, titleModel)


[MEDIUM] provider.CloneWithOptions return value is not nil-checked before appending to models

provider.CloneWithOptions may return nil depending on its implementation (e.g., if the base model type doesn't support cloning). A nil provider.Provider interface value appended to models and passed to ai.WithModels would cause a nil-pointer dereference (panic) inside ai.completion.stream() when the interface method is called.

The baseModel == nil guard above only filters nil inputs; it does not protect against a nil output from CloneWithOptions.

Fix: add a nil check on the result:

titleModel := provider.CloneWithOptions(ctx, baseModel, ...) if titleModel == nil { continue } models = append(models, titleModel)

shaj13 requested a review from a team as a code owner April 15, 2026 22:06

introduce pkg/ai as core LLM completion layer

601d753

Add new pkg/ai package that extracts and centralizes model interaction logic from runtime. The package reuses existing types from chat, tools, and provider packages without moving them.

shaj13 force-pushed the pkg/ai branch from fef9cc6 to 601d753 Compare April 15, 2026 22:14

aheritier requested changes May 6, 2026

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aheritier reviewed May 6, 2026

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docker-agent Bot reviewed May 6, 2026

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Assessment: 🔴 CRITICAL

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shaj13 commented Apr 15, 2026 •

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