[1905 by GPT-5.6 Sol] Make /use change only the PR model label

docs/docs/features/agents-and-models.md

@@ -68,7 +68,7 @@ Reasoning flags require Claude Code >= 2.1.68 and Codex CLI >= 0.144.0. Saving a
 
 ## Model Labels
 
-Every model has a GitHub label of the form `llm-<agent>-<model-alias>`. Add one to an issue (together with your trigger label, such as `AI`) to route that issue to the model. The same identity follows the run through the system: task records show the selected agent and model, and branch names include the model identifier for traceability.
+Every model has a GitHub label of the form `llm-<agent>-<model-alias>`. For ordinary issues, add the trigger label (such as `AI`) by itself and ProPR uses the configured default model. Add one model label only when you want an explicit override. The same identity follows the run through the system: task records show the selected agent and model, and branch names include the model identifier for traceability.
 
 Adding **several** model labels to one issue fans the work out into one job per model label: each model gets its own run, its own worktree and branch, and its own pull request. Compare the PRs, merge the best one, and close the rest. If a `base-<branch>` label is also present, the fan-out is per base × per model.
 
@@ -84,7 +84,7 @@ The same aliases work in PR comments (the `llm-` prefix is optional; the raw cat
 
 ```
 /switch claude-opus5      # future follow-ups on this PR use this model
-/use codex-gpt56-sol      # one follow-up with this model
+/use codex-gpt56-sol      # change this PR's model label
 /review claude-opus5 codex-gpt56-sol   # independent reviews from two models
 ```
 

docs/docs/features/pr-commands.md

@@ -23,15 +23,15 @@ To **take over an existing PR** for ongoing work (so that natural follow-up comm
 | `/fix` | You want to apply a `/review`'s pending suggestions | Yes | [`/fix`](#fix) |
 | `/merge` | You want the base branch merged into the PR branch | Maybe, if conflicts need resolution | [`/merge`](#merge) |
 | `/switch <model-id>` | You want future PR work to use a different model | No, unless you include follow-up instructions | [`/switch`](#switch) |
-| `/use <model-id>` | You want one immediate follow-up run with a temporary model | Yes | [`/use`](#use) |
+| `/use <model-id>` | You want to change the PR's model label | No | [`/use`](#use) |
 | `/ultrafix` | You want an automated review-fix loop | Yes | [`/ultrafix`](#ultrafix) |
 
 ## Syntax Rules
 
 - The slash command must be on the first line of the PR comment. A comment with leading blank lines or text before the command is treated as a normal follow-up comment.
 - Arguments go on the same line as the command (for example `/review llm-claude-opus5` or `/ultrafix goal=8 max=10`).
-- Lines below the command become extra instructions for the run.
-- Both top-level PR comments and line-level review comments are processed; line-level comments carry their file, line, and diff context to the agent.
+- Lines below the command become extra instructions when the command queues work. `/use` ignores trailing text because it only changes a label.
+- Both top-level PR comments and line-level review comments are processed; when a command queues work, line-level comments carry their file, line, and diff context to the agent.
 
 ## Model IDs
 
@@ -170,14 +170,13 @@ Without instructions, `/switch` only updates the label and makes no code changes
 
 ### `/use`
 
-`/use` runs one immediate follow-up task with a temporary model:
+`/use` changes the PR's managed model label:
 
 ```text
 /use <model-id>
-Please investigate the flaky test failure and update the PR.
 ```
 
-The PR's model label keeps its current value. Later work returns to the PR's configured model unless you use `/switch` or another `/use`. Like `/switch`, `/use` takes one model argument, and the agent sees only your instructions, without the command syntax.
+ProPR resolves a supported short alias or full `llm-*` label, removes the PR's other managed model labels, and adds the selected canonical label. All unrelated labels are preserved. `/use` does not queue work; any trailing text is ignored. Post a separate follow-up comment when you want the selected model to do work.
 
 ### Choosing A Model
 
@@ -187,7 +186,7 @@ Use routing when:
 
 - A model is better suited to the task
 - The current model is stuck
-- You want a one-off second opinion
+- You want future work on the PR to use a different model
 - You need to work around provider capacity or rate limits
 
 ## Ultrafix And Branch Updates

docs/docs/operations/troubleshooting.md

@@ -99,7 +99,7 @@ Then check credentials, branch settings, and agent configuration — the usual c
 Recovery runs through the PR conversation:
 
 - Add a clearer follow-up comment with stronger instructions.
-- `/switch <model-id>` to change the PR's model going forward, or `/use <model-id>` for a one-off task with a different model.
+- `/use <model-id>` to change the PR's model label without queuing work, or `/switch <model-id>` when you also need its optional follow-up behavior.
 - `/review` then `/fix`, or `/ultrafix` for an automated review-fix loop (remove the `ultrafix` PR label to stop it).
 - Re-run with a smaller scope — see [Work Splitting](../features/work-splitting.md).
 - Undo a bad commit with `propr task revert owner/repo <pr> <sha> <issue>`, which runs a signed system task (authorized via `SYSTEM_TASK_SECRET`) that resets the branch and force-pushes.

docs/docs/tutorials/usage.md

@@ -79,7 +79,7 @@ Use slash commands only for specific actions:
 - `/fix` applies unprocessed AI review comments generated by `/review`.
 - `/merge` merges the base branch into the PR branch, attempts automatic conflict resolution, and reports back.
 - `/switch <model-id>` changes the PR's model label going forward.
-- `/use <model-id>` runs one follow-up task with that model without changing the PR's model.
+- `/use <model-id>` changes the PR's managed model label without queuing work.
 - `/ultrafix` runs a review-fix loop. Parameters: `goal=<score>`, `max=<cycles>`, `pause=<seconds>`, `model=<model-id>`, for example `/ultrafix goal=9 max=5`. It waits for CI checks and PR inactivity between cycles. The `ultrafix` PR label is the circuit breaker — remove it to stop the loop.
 
 See [PR Slash Commands](../features/pr-commands.md).

packages/core/src/webhook/commentEventHandler.ts

@@ -17,11 +17,12 @@ import { handleMergeCommand } from './mergeConflictDetector.js';
 import { parseSlashCommand, buildCommandMeta } from './slashCommandParser.js';
 import type { CommandMeta, UltrafixCommandMeta } from './slashCommandParser.js';
 import { safeUpdateLabels } from '../utils/github/labelOperations.js';
-import { resolveModelAlias } from '../config/modelAliases.js';
+import { resolveModelAlias, resolveReviewModels } from '../config/modelAliases.js';
 import { MODEL_INFO_MAP } from '../config/modelDefinitions.js';
 import { getBotUsername } from '../daemon/configLoader.js';
 import { AgentRegistry } from '../agents/AgentRegistry.js';
 import type { DeliveryDisposition } from '../intake/routingWebSocketProtocol.js';
+import { buildAgentModelLlmLabel, buildDynamicLlmLabel, MAX_GITHUB_LABEL_LENGTH, shortHash } from '@propr/shared';
 
 export interface UltrafixDeps {
     loadUltrafixRatingGoal: () => Promise<number>;
@@ -283,19 +284,11 @@ async function handleSlashCommand(opts: SlashCommandHandlerOptions): Promise<voi
         return;
     }
 
-    if (commandMeta.mode === 'use' && commandMeta.models.length === 0) {
-        correlatedLogger.warn({ pullRequestNumber: prNumber, commentId: comment.id, commentAuthor }, '/use command requires a model argument, ignoring');
+    if (commandMeta.mode === 'use') {
+        await handleUseCommand({ commandMeta, comment, commentAuthor, eventContext, payload, config, correlationId, correlatedLogger });
         return;
     }
 
-    if (commandMeta.mode === 'use' && commandMeta.models.length > 0) {
-        const resolvedModel = resolveModelAlias(commandMeta.models[0]);
-        if (!await isKnownOrConfiguredModel(resolvedModel)) {
-            correlatedLogger.warn({ pullRequestNumber: prNumber, invalidModels: [resolvedModel] }, '/use command contains unrecognized model(s), ignoring');
-            return;
-        }
-    }
-
     const manualTakeover = await fenceManualCommand({ commandMeta, comment, eventContext, config, correlatedLogger });
 
     correlatedLogger.info({ pullRequestNumber: prNumber, commentId: comment.id, commentAuthor, command: commandMeta.mode }, `/${commandMeta.mode} command detected, enqueuing job`);
@@ -325,6 +318,184 @@ async function handleSlashCommand(opts: SlashCommandHandlerOptions): Promise<voi
     await enqueueNewCommentJob(strippedComment, commentAuthor, eventContext, { payload, redisClient, PR_FOLLOWUP_TRIGGER_KEYWORDS: config.PR_FOLLOWUP_TRIGGER_KEYWORDS, MODEL_LABEL_PATTERN: config.MODEL_LABEL_PATTERN, correlationId, commandMeta, commentRevisionIdentity: manualTakeover?.commentRevisionIdentity });
 }
 
+type UseCommandOptions = Omit<SlashCommandHandlerOptions, 'parsedCommand'> & { commandMeta: CommandMeta & { mode: 'use' } };
+
+function buildPrefixedDynamicModelLabel(prefix: string, agentAlias: string, modelId: string): string | null {
+    const canonicalLabel = `${prefix}${agentAlias}~${modelId}`;
+    if (canonicalLabel.length <= MAX_GITHUB_LABEL_LENGTH) return canonicalLabel;
+
+    const hash = shortHash(modelId);
+    const maxAliasLength = Math.max(1, MAX_GITHUB_LABEL_LENGTH - `${prefix}~-x-${hash}`.length);
+    const sanitizedAlias = agentAlias
+        .replace(/[^a-zA-Z0-9_.-]/g, '-')
+        .slice(0, maxAliasLength)
+        .replace(/[^a-zA-Z0-9]+$/, '');
+    const labelAlias = sanitizedAlias || 'agent'.slice(0, maxAliasLength);
+    const modelPrefixBudget = MAX_GITHUB_LABEL_LENGTH - `${prefix}${labelAlias}~-${hash}`.length;
+    const fallbackPrefix = 'model'.slice(0, Math.max(1, modelPrefixBudget));
+    const modelPrefix = modelId
+        .replace(/[^a-zA-Z0-9_.-]/g, '-')
+        .slice(0, Math.max(1, modelPrefixBudget))
+        .replace(/[^a-zA-Z0-9]+$/, '');
+    const hashedLabel = `${prefix}${labelAlias}~${modelPrefix || fallbackPrefix}-${hash}`;
+    return hashedLabel.length <= MAX_GITHUB_LABEL_LENGTH ? hashedLabel : null;
+}
+
+function applyModelLabelPrefix(defaultLabel: string, prefix: string, agentAlias: string, modelId: string): string | null {
+    if (!defaultLabel.startsWith('llm-')) {
+        return defaultLabel.length <= MAX_GITHUB_LABEL_LENGTH ? defaultLabel : null;
+    }
+
+    const suffix = defaultLabel.slice('llm-'.length);
+    if (suffix.includes('~')) {
+        return buildPrefixedDynamicModelLabel(prefix, agentAlias, modelId);
+    }
+
+    const staticLabel = `${prefix}${suffix}`;
+    return staticLabel.length <= MAX_GITHUB_LABEL_LENGTH
+        ? staticLabel
+        : buildPrefixedDynamicModelLabel(prefix, agentAlias, modelId);
+}
+
+async function resolveCanonicalModelLabel(
+    target: string,
+    modelLabelPattern: string,
+    correlatedLogger: ReturnType<typeof logger.withCorrelation>,
+    prNumber: number,
+): Promise<string | null> {
+    try {
+        const modelLabelRegex = new RegExp(modelLabelPattern);
+        const targetMatch = modelLabelRegex.exec(target);
+        const routingTarget = targetMatch?.[1] || target;
+        const [resolution] = await resolveReviewModels([routingTarget]);
+        const registry = AgentRegistry.getInstance();
+        const agent = registry.getAgentByAlias(resolution.agentAlias);
+        if (!agent) {
+            correlatedLogger.warn(
+                { pullRequestNumber: prNumber, target },
+                '/use target is unknown, disabled, or unsupported; model label was not changed',
+            );
+            return null;
+        }
+
+        const modelInfo = MODEL_INFO_MAP[resolution.model];
+        const defaultLabel = modelInfo
+            ? buildAgentModelLlmLabel(agent.config.type, agent.config.alias, modelInfo)
+            : buildDynamicLlmLabel(agent.config.alias, resolution.model);
+        const { prefix, derived } = modelLabelPrefix(modelLabelPattern);
+        if (!derived) {
+            correlatedLogger.warn(
+                { pullRequestNumber: prNumber, modelLabelPattern },
+                'Could not derive label prefix from MODEL_LABEL_PATTERN; /use cannot safely select a model label',
+            );
+            return null;
+        }
+
+        const canonicalLabel = applyModelLabelPrefix(defaultLabel, prefix, agent.config.alias, resolution.model);
+        if (!canonicalLabel) {
+            correlatedLogger.error(
+                { pullRequestNumber: prNumber, modelLabelPattern },
+                '/use could not build a canonical model label within GitHub\'s label length limit',
+            );
+            return null;
+        }
+        const canonicalMatch = modelLabelRegex.exec(canonicalLabel);
+        const canonicalRoutingToken = canonicalMatch?.[1];
+        if (!canonicalRoutingToken) {
+            correlatedLogger.error(
+                { pullRequestNumber: prNumber, canonicalLabel, modelLabelPattern },
+                '/use resolved a canonical label that does not match MODEL_LABEL_PATTERN',
+            );
+            return null;
+        }
+
+        let routedResolution: Awaited<ReturnType<typeof resolveReviewModels>>[number];
+        try {
+            [routedResolution] = await resolveReviewModels([canonicalRoutingToken]);
+        } catch (error) {
+            correlatedLogger.error(
+                { pullRequestNumber: prNumber, canonicalLabel, canonicalRoutingToken, error: (error as Error).message },
+                '/use resolved a canonical label that cannot route back to the selected model',
+            );
+            return null;
+        }
+        if (routedResolution.agentAlias !== resolution.agentAlias || routedResolution.model !== resolution.model) {
+            correlatedLogger.error(
+                {
+                    pullRequestNumber: prNumber,
+                    canonicalLabel,
+                    selectedAgentAlias: resolution.agentAlias,
+                    selectedModel: resolution.model,
+                    routedAgentAlias: routedResolution.agentAlias,
+                    routedModel: routedResolution.model,
+                },
+                '/use resolved a canonical label that routes to a different model',
+            );
+            return null;
+        }
+        return canonicalLabel;
+    } catch (error) {
+        correlatedLogger.warn(
+            { pullRequestNumber: prNumber, target, error: (error as Error).message },
+            '/use target is unknown, disabled, or unsupported; model label was not changed',
+        );
+        return null;
+    }
+}
+
+async function handleUseCommand(opts: UseCommandOptions): Promise<void> {
+    const { commandMeta, comment, commentAuthor, eventContext, config, correlatedLogger } = opts;
+    const { prNumber, owner, repo } = eventContext;
+
+    if (commandMeta.models.length === 0) {
+        correlatedLogger.warn({ pullRequestNumber: prNumber, commentId: comment.id, commentAuthor }, '/use command requires a model argument, ignoring');
+        return;
+    }
+
+    const modelLabelPattern = config.MODEL_LABEL_PATTERN || '^llm-(.+)$';
+    const canonicalLabel = await resolveCanonicalModelLabel(commandMeta.models[0], modelLabelPattern, correlatedLogger, prNumber);
+    if (!canonicalLabel) return;
+
+    const { prLabels } = await getLivePRBranchAndLabels({ owner, repo, prNumber });
+    const canonicalLabelIdentity = canonicalLabel.toLowerCase();
+    const existingModelLabels = prLabels.filter(label => label.name.startsWith('llm-')).map(label => label.name);
+    const labelsToRemove = existingModelLabels.filter(label => label.toLowerCase() !== canonicalLabelIdentity);
+    const targetPresent = prLabels.some(label => label.name.toLowerCase() === canonicalLabelIdentity);
+
+    if (labelsToRemove.length === 0 && targetPresent) {
+        correlatedLogger.debug({ pullRequestNumber: prNumber, modelLabel: canonicalLabel }, '/use model label is already active');
+        return;
+    }
+
+    const labels = [
+        ...prLabels
+            .filter(label => !label.name.startsWith('llm-') && label.name.toLowerCase() !== canonicalLabelIdentity)
+            .map(label => label.name),
+        canonicalLabel,
+    ];
+
+    try {
+        const octokit = await getAuthenticatedOctokit();
+        await octokit.request('PUT /repos/{owner}/{repo}/issues/{issue_number}/labels', {
+            owner,
+            repo,
+            issue_number: prNumber,
+            labels,
+        });
+    } catch (error) {
+        correlatedLogger.error(
+            { pullRequestNumber: prNumber, modelLabel: canonicalLabel, error: (error as Error).message },
+            '/use failed to update the PR model label',
+        );
+        return;
+    }
+
+    correlatedLogger.info(
+        { pullRequestNumber: prNumber, modelLabel: canonicalLabel },
+        '/use updated the PR model label',
+    );
+}
+
 type SwitchCommandOptions = Omit<SlashCommandHandlerOptions, 'parsedCommand'> & { commandMeta: CommandMeta & { mode: 'switch' } };
 
 async function handleSwitchCommand(opts: SwitchCommandOptions): Promise<void> {

packages/core/src/webhook/slashCommandParser.ts

@@ -46,7 +46,7 @@ export interface SwitchCommandMeta {
 
 export interface UseCommandMeta {
     mode: 'use';
-    /** Target model labels for single-run override */
+    /** Target model label to make active on the PR */
     models: string[];
     /** Extra instructions from lines below the command */
     instructions: string;
@@ -120,7 +120,8 @@ function normalizeModelLabel(label: string): string {
  * For `/fix`: captures everything after `/fix` as instructions.
  * For `/merge`: returns a simple merge marker.
  * For `/switch`: extracts single model target and optional instructions.
- * For `/use`: extracts single model for one-time override and optional instructions.
+ * For `/use`: extracts the single model label target. Trailing text is parsed for
+ * compatibility but ignored by the webhook handler.
  * For `/ultrafix`: parses positional goal or named key=value arguments.
  */
 export function buildCommandMeta(parsed: ParsedSlashCommand): CommandMeta {

src/shared/slashCommandsBlock.ts

@@ -13,7 +13,7 @@ export function buildSlashCommandsBlock(): string {
         '| `/review` | Request an AI code review | `/review` or `/review claude-sonnet` |',
         '| `/fix` | Implement fixes for issues found by `/review` | `/fix` or `/fix address the null check issue` |',
         '| `/switch` | Change the AI model for this PR | `/switch claude-opus` |',
-        '| `/use` | Override the model for a single follow-up run | `/use claude-sonnet` |',
+        '| `/use` | Change this PR\'s model label | `/use claude-sonnet` |',
         '| `/ultrafix` | Loop review→fix cycles until score goal is met | `/ultrafix` or `/ultrafix goal=8 max=10` |',
         '',
         '</details>',